Fraunhofer Newspaper Segmenter & Korrektor

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Introduction

The Korrektor is a manual post-correction tool for automatically processed newspaper scans. By loading the result XML files into the software, it is possible to correct automatically detected layout elements, texts and other properties. The scanned documents are displayed in two separate windows to allow for a detailed inspection. Results can be edited using context menus, drag and drop and keyboard shortcuts.

System Requirements

Hardware: Standard PC with 1 GB RAM (or more)

Operating system: Linux or Windows

Software:Java runtime environment (>= 6.0)

Licensing

The tool is produced at the Fraunhofer Institute for Intelligent Analysis and Information Systems (IAIS) in Sankt Augustin, Germany.

For more information on terms and conditions to use the tool, please contact Fraunhofer IAIS, Department NetMedia:

Dr. Joachim Köhler

Joachim.koehler@iais.fraunhofer.de

Graphical User Interface

The graphical user interface of the Korrektor consists of three views displayed in individual windows: the Main Window (Error: Reference source not found), used for editing metadata, article and text information, the Word Highlighter (Error: Reference source not found), displaying the currently selected word in the scanned document, and the Issue Viewer (Error: Reference source not found), displaying the currently loaded issue.

NewspaperSegmentor image001.png

The following subsections give a brief overview of the individual views. The most common correction functions are explained in section 4Error: Reference source not found.

Main Window

The Navigation Bar offers basic features like file operations (File), editing operations (Edit) and additional views (View).

The Metadata View (issue or page) shows information about the currently opened XML file. Upon opening a file containing a full issue, the following fields are available:

  • Title: Newspaper title
  • Date: Issue date
  • Issue: Issue number
  • Publisher: Newspaper publisher
  • Edition: Newspaper edition
  • Pages: Number of pages

In contrast, if the opened XML file contains only a single page, the following fields are available:

  • Category: page category (e.g. title page, sports, politics)
  • Date: Issue date for this page
  • Page: Page number in issue
  • Source: Page source (e.g. newspaper title)

All field values can be updated or filled in.


The Article View shows a list of the currently detected articles. The color column indicates the color using which the articles are visualized in the Issue Viewer window. If an article contains a title block, the contents of this block is visible in the title column. The pages column gives an overview of the pages where each article can be found (relevant if an article spans more than one page). By choosing one of the articles via a left mouse click, the article is loaded into the Article Editor and can be edited. The context menu (right click) offers two options:

  • Edit Article: Edit an article in the Article Editor
  • Remove Article: Remove an article and release all its associated blocks

The Article Editor is composed of three main components: article header, text editor panel and article footer. If either a whole article or a single block belonging to an article is selected, the frame of the text editor will be drawn in the color of the respective article. In case the currently selected block has not yet been assigned to any article, the frame of the text editor will be painted in grey. The article header and footer areas contain metadata about the article. Similarly as before, if any single block belonging to an article is selected, the metadata shown will be that of the respective article. For unassigned blocks, all fields within the article header and footer will be empty.


The article header starts with four read-only fields which display the text content of the regions marked as roof title, title, subtitle and byline. For any of the aforementioned fields, a mouse click on the field will result in the selection of the respective block within the article. Its text will then be automatically shown in the text editor and can be freely modified. The words marked as unsure by the OCR process are highlighted in red. If at one moment a single article block is selected (and not a whole article), then the button “Edit article…” is activated. By clicking this button, one may switch to the editing of the whole article. This is useful for example for quickly switching to whole-article editing right after correcting the text of its titles and its byline.


Below the title fields there are several editable metadata fields, namely Author, Category, Location and Date/Time. The field Category is represented as a combo box and may only be assigned a value out of a preset list of categories.

The text editor area allows the direct editing of the article text. A number of tools exist which are meant to facilitate an efficient text editing:

Word correction tool:

Words which have been wrongly recognized by the OCR process may be corrected on an individual basis. This is an important observation, because it means that it is not allowed to delete or add entire words and word breaks. The reason for this restriction is simple: deleting or adding entire words may cause the program to be unable to ensure a two-way correspondence between the remaining/ newly-added words and their exact location in the document image.

NewspaperSegmentor image002.png

Synchronized Display:

The word at the current cursor position within the text editor will be automatically marked in red in the Word Highlighter window, which shows an excerpt of the original document image. The automatic updating of the Word Highlighter window is meant to ensure that a fluent correction of the article text is possible at a glance. Analogously, the content of the Issue Viewer pane will also be automatically updated to reflect the cursor position and will do so by marking the block containing the current word with a wide frame. CTRL + left mouse clicking a word within the text editor will take the user directly to its corresponding block in the Issue Viewer. This is helpful for example for quickly finding small blocks (which would otherwise be hard to see at lower magnification settings) in the Issue Viewer.

Context menu:

A right click with the mouse within the text editor area opens a context menu. The context menu contains several block editing functions which are described in more detail in section (Issue Viewer – Context menu). Note that the function Delete Block is deactivated on purpose in order to prevent accidental deletions of entire text blocks (deleting blocks can thus only be performed in the Issue Viewer).

At the bottom of the Article Editor pane two tables may be found: the upper one contains a listing of all foot notes attached to the article, whereas the lower table contains the list of all attachments and their corresponding caption regions. All non-text components of an article (e.g. photographs, drawings) are denoted as attachments. The possible block types are described in section Issue Viewer.

Word Highlighter

The Word Highlighter view pane shows a small section of the document image. Its content is synchronized with the text editor pane as described in the previous section. In addition to the synchronization feature, the current word is highlighted in red for better visibility and faster editing.

Issue Viewer

The Issue Viewer shows the original document images. On top of the document image the text blocks found by the automatic segmentation/ manually created by the user are displayed semi-transparently in the color of the article which they were assigned to. Unassigned text blocks are depicted using hollow rectangles. Editing functions are available via left mouse click (multi-block selection), right mouse click (opening a context menu) and via drag and drop (assigning blocks to articles).

The current zoom level for the document image can be adjusted between 10% and 100% via the drop box in the upper left corner of the Issue Viewer. Note that manually inputting different zoom level values than those from the list of presets is also possible. This can be done via a left mouse click on the zoom level box and then typing the desired values via the keyboard, followed by the CR key. The Issue Viewer panel also allows the increasing or decreasing of the zoom level in 10% increments using the keys “+” and “-“, respectively. By pressing the “w” key, the zoom level will be automatically adjusted such that the width of the document corresponds exactly to the current width of the Issue Viewer window. Analogously, the “h” key has the effect of resizing the document image such that its height corresponds exactly to the height of the Issue Viewer window.

Page Segmentation Display Panel

The page blocks discovered by the automated page segmentation process or manually created by the user are displayed via semi-transparent rectangular frames. Depending on the status of each block, its background color will change accordingly as follows:

    • blue: Blocks which have not yet been assigned to an article.
    • non-blue: Blocks which have been assigned to an article. Their background color corresponds to the color of the containing article. The number in the upper left corner of the block represents the position of the block in the article’s reading order. Non-text blocks, captions and text boxes are numbered separately, as they can generally be read in any order. The ordering of such blocks will initially be automatically computed based on the document layout. Changing the position of a block within the reading order of an article can be accomplished via the keys “<” and “>”. The “<“ key moves a block to an earlier position within the reading order, while the “>” key moves a block towards the end of the reading order. The ordering of nearby blocks is then updated automatically to best reflect the changes performed by the user.
    • black frame: An additional black frame around a block signals that the respective block belongs to the current user selection. A multi-block selection can be processed as a whole via the functions available in the context menu (see Multi-Block-Functions).
NewspaperSegmentor image003.png

Context Menu for Single Block Selections

The context menu is displayed upon pressing the right mouse button. A different context menu is available depending on whether the current user selection consists of a single or multiple page blocks. The current section describes the functionality available for single block selections. The functions available in the context menu are:

  • Edit Article: This option is only available if the selected block has already been assigned to an article. Using this option has the effect of loading the entire article (i.e. all text blocks belonging to the article) into the editor, where it can be modified by the user.
  • Edit Block: The selected block is loaded into the text editor, where it can be inspected and modified. A simpler equivalent to this option is via a single left mouse click on a block.
  • Create Article: Creates a new article from the selected block. The created article is automatically loaded into the text editor. Note that this option is also available for blocks already assigned to articles. In this case the removal of the block from its containing article will happen automatically. The block will be marked directly as article title. The function “Create Article” may also be activated via the keyboard combination CTRL+a.
  • Exclude: Removes a block from an article. A simpler equivalent to using this context menu option is pressing the “Backspace” key when a single block is selected.
  • Undo Selection: Removes a block from a multi-block selection (see 3.1.3). This menu option is only available for blocks belonging to a multi-block selection.
  • Add to Selection: Only available for blocks not yet selected into the current multi-block selection. For such blocks, it has as effect the addition of the respective block to the multi-block selection.
  • Category: This menu option is only available for blocks already assigned to an article. It allows the labeling of the selected block with a category. The list of all available categories may be loaded via the application preferences.
  • Type: Set one of several pre-defined physical types for the selected block. The pre-defined page block types available are the following:
    • Text: Regular text block
    • Graphic: Line art (hand drawing)
    • Picture: Halftone image/ photograph
    • Table: any kind of table
  • Label: Only available for blocks marked as belonging to articles. One of the following logical labels may be chosen fort text blocks (all other block types will be automatically marked as attachment):
  • Roof title: small/underlined title usually placed above the main title of an article
  • Title: main title of an article
  • Subtitle: subtitle of an article
  • Byline: gives the name, the date, and often the position of the writer of the article. Bylines are traditionally placed between the headline and the text of the article, although some printed media place bylines at the bottom of the article
  • Lead: lead paragraph(s). It usually occurs together with the headline or title. It precedes the main body of the article, and it gives the reader the main idea of the story.
  • Body: body of an article, usually containing the bulk of its text
  • Intermediate Title: all intermediary titles following the subtitle and dividing longer articles into parts
  • Footnote: footnote assigned to an article

Depending on their label, blocks will be displayed and handled differently in the Article Editor pane (see section ).

  • Delete Block: Completely discards existing blocks from the document page. The deleted block is afterwards no longer available for any kind of processing. A shortcut for this function is by pressing the SHIFT+Backspace key combination. Note that any text contained in the deleted block will still be remembered as being present at the respective location, albeit this is done “invisibly”. Consequently, in case a new block is created at the same position, the new text block will contain the portion of the text located within its bounds.

Context Menu for Multi-Block Selections

The Korrektor allows the processing of multiple blocks at once via multi-block selections and a corresponding context menu. Multiple blocks can be selected by pressing the left mouse button and dragging the mouse in a direction with the left mouse button still pressed. The blocks located mostly within the drawn rectangle will be marked das belonging to the current selection. Note that during the selection operation no key may be pressed. The selected blocks can afterward be modified as a whole via the following options from the context menu:

  • Create Block: Only available immediately after the multi-block selection was performed. It allows the creation of a new block having one of the following types: Text, Picture, Graphic, Table. The result is similar to that which may be obtained via the extended keyboard combination ALT + mouse selection (see section 3.1.5). Note that Create Block does not technically belong to the category of multi-block functions. This is because the selected blocks are not modified in any way (i.e. they are not merged or incorporated into the new block).
  • Single Block Menu: This menu item allows one to access the context menu options for single blocks, if so desired. The context menu for single blocks was presented in the previous section.
  • Merge Blocks: All blocks belonging to the selection are merged into a single block. In the process, the old blocks are discarded. The new bounding box of the merged region is computed as the smallest box containing all selected blocks. An alternative shortcut for this option is the extended shortcut CTRL + ALT + mouse selection (see section 3.1.5).
  • Create Article: Creates a new article from the selected blocks. This function may also be called via the keyboard shortcut CTRL+a.
  • Exclude All: All selected blocks are removed from their containing article(s) and further remain as independent/ unassigned blocks. The equivalent shortcut for this context menu item is the Backspace key.
  • Undo Selection: The block selection is reset (i.e. all selected blocks are removed from the selection).
  • Category: Set the category field for the selected blocks. If all selected block already have the same category, the respective category will be shown as marked in the category list. If some of the selected blocks have different categories, no default category will be marked.
  • Type: Set the block type for all selected blocks. If all selected blocks have the same type, the respective type will be shown as marked in the list of allowable types, otherwise no type will be marked by default. More information about the possible physical block types can be found in section 3.1.2.
  • Label: Set the block logical label for all selected blocks. If all selected blocks already have the same logical label, it will be shown as marked in the label list, otherwise no label will be marked by default. More information about the possible logical labels may be found in section 3.1.2.
  • Delete Blocks: Discard the selected blocks completely. This function may also be called via the keyboard shortcut SHIFT+Backspace. Another alternative is holding the SHIFT key pressed while performing a multi-block selection with the mouse so as to immediately discard all blocks in the selection rectangle (see also section 3.1.5).

Drag & Drop Functionality

In addition to the functionality offered in the context menus, a few common operations may also be performed comfortably via drag and drop. The following drag & drop-based operations are supported:

  • Assigning a block to an/another article: Press and hold the left mouse button over an existing block. Drag the block (i.e. move mouse with left button still pressed) on top of another block which has already been assigned to an article and then release the mouse button. The initial block will then be assigned to the respective article. This operation works exactly the same for independent as well as previously assigned blocks. Alternatively it is possible to drag a block directly on top of the text editor area, case in which the block will be assigned to the article opened there.
  • Marking a block as caption: If a text block is dragged and dropped (see above) on top of an attachment (e.g. photograph, line-art and table), it will automatically be labeled as caption for the respective attachment. This works for all blocks, regardless whether they were or were not already part of the article containing the non-text attachment.
  • Removing a block from an article: By performing a drag & drop (see above) of a block assigned to an article on top of one which is unassigned, the former shall be marked as unassigned. Note that this functionality is equivalent to the Exclude function available in the context menu.

We have previously seen that it is possible to open a single text block for editing via the Edit Block item from the context menu. The same effect can be achieved via a simple left mouse click on a text block. In case the CTRL key is pressed during the mouse click, the whole article is loaded into the text editor.

Extended Shortcuts

Three modifier keys (CTRL, SHIFT and ALT) may be used in conjunction with the mouse as part of extended shortcuts so as to facilitate the execution of common operations. The possible shortcuts are described in the following.

CTRL: The CTRL key is generally used to signal that a certain operation does not merely refer to a single block, but to its entire containing article. The following extended shortcuts are currently supported:

  • CTRL + left mouse button: The whole article (not only the clicked block) will be loaded into the text editor. The view will be automatically centered on the first block (in reading order) of the article.
  • CTRL + Drag&Drop: The whole article containing the dragged block (not only the dragged block itself) will be merged into the destination article.
  • CTRL + ALT + mouse (area) selection: If during the mouse selection of a rectangular area both keys CTRL and ALT are kept pressed, all blocks within the respective area will be merged into a new block. If all selected blocks belonged to the same article, then the new block will also belong to the respective article.

SHIFT: The SHIFT key is generally meant for actions related to the deletion or removal of single or multiple blocks. The following extended shortcuts are currently supported:

  • SHIFT + mouse (area) selection: By keeping the SHIFT key pressed while performing an area selection operation with the mouse, all blocks located completely within the bounds of the selected rectangle will be deleted.

ALT: The ALT key facilitates functionality related to the creation of new blocks and articles. The following extended shortcuts are currently supported:

  • ALT + mouse area selection: If the ALT key is kept pressed during the selection of a certain area with the mouse, then a new text block will be created from the respective rectangle. All words located within the marked area will be included in the new block, as long as they have not already been assigned to an existing block.

Common Correction Functions

In the following one may find a detailed step by step description of the basic user actions required in order to perform some of the most important correction operations. The elements referenced within (such as GUI elements, drag & drop specifics, a.s.o.) have been described in chapter 3.

Opening Additional Views

If the views Issue Viewer and/or Word Highlighter have been (un)intentionally closed by the user, they can be re-opened as follows:

  • Left mouse click on the View element located in the menu bar of the main application window
  • In the pop-up menu which opens choose via a left mouse click the view which shall be opened:
    • Issue: Opens the Issue Viewer window
    • Word Highlighter: Opens the Word Highlighter window

Creating a New Text Block

The creation of a new text block may be accomplished as follows:

  • Go to the Issue Viewer window
  • Move the mouse cursor to one of the corners of the desired rectangular area
  • Press and hold the ALT key
  • Press and hold either mouse button
  • Move the mouse cursor to the opposite corner of the desired rectangular area while keeping both the mouse button and the ALT key pressed
  • Release the mouse button first, followed by the ALT key. A new block (highlighted via a blue frame) is created using as opposite corners the start and end point of the drag operation.
  • All previously existing words located within the marked area will be transferred to the newly created block, as long as they were not part of an already existing text block.

Creating a New Article

There exist several alternatives for creating a new article:

  1. Via the menu bar in the main application window:
  • Go to the main application window of the Korrektor
  • Left mouse click on the menu bar item Edit
  • Left mouse click on the item New Article from the pop-up menu
  • Input the desired article metadata using the Article Editor pane
  • Append any existing blocks to the created article (see section )
  1. Via the context menu in the Issue Viewer:
  • Go to the Issue Viewer window
  • Right mouse click on a block which shall be part of the new article
  • Select the item Create Article from the context menu
  • A new article is now created and shown in the main application window. The text block first added to the article is automatically marked as article title.
  1. Via a keyboard shortcut:
  • In the Issue Viewer window, move the mouse cursor over a block. If the block belongs to the current multi-block selection, all blocks from the selection will be highlighted.
  • Press the key combination CTRL+a.
  • A new article is now created and the first text block added is automatically marked as article title

Appending a Block to an Article

Blocks can be appended to articles via drag & drop, as follows:

  • Go to the Issue Viewer window
  • Move the mouse cursor over the block which shall be appended
  • Press and hold either mouse button
  • Move the mouse cursor (while keeping the mouse button pressed) over a block belonging to the article where the initial block shall be assigned to. Alternatively one can drag the block to the text editor area in the main application window. The article to which the block shall be appended must have already been opened for editing.
  • Release the mouse button. The block is now appended to the desired article.

Opening a Text Block for Editing

Any text block can be opened for further editing in the Article Editor pane via the context menu from the Issue Viewer window, as in the following:

  1. Using the context menu in the Issue Viewer window:
  • Go to the Issue Viewer window
  • Move the mouse cursor over the text block which will be edited
  • Press the right mouse button
  • Left mouse click on the item Edit Block from the context menu
  • The block text is now shown in the Article Editor pane within the main application window and can be further modified there
  1. Via mouse clicking in the Issue Viewer window:
  • Go to the Issue Viewer window
  • Click with the left mouse button on the block which will be edited
  • The block text is now shown in the Article Editor pane within the main application window and can be further modified there
  1. Via the article metadata fields in the main Korrektor application window (only possible for certain logical block labels and only when their containing article is already open for editing):
  • Go to the main Korrektor application window
  • Find the desired block in the Article Header or Article Footer panels, according to its logical label (see section on the Article editor)
  • Left mouse click on the found field
  • The block text is now shown in the Article Editor pane within the main application window and can be further modified there

Setting the Block Type

The physical type of a block can be readily set either via a keyboard shortcut (see table in section 5) or via the context menu in the Issue Viewer window. If opting for the latter variant, one must do the following:

  • Go to the Issue Viewer window
  • Move the mouse cursor over the block whose physical type shall be set
  • Press the right mouse button
  • Move the mouse cursor over the item Type in the freshly opened context menu
  • Select a block type from the pop-up list via a click using either mouse button
  • The physical type of the block is now changed and the block visualization is automatically updated to reflect the new block type (if necessary)

Setting the Block Label

The logical label of a block can be set either via a keyboard shortcut (see table in section 5) or via the context menu in the Issue Viewer window, as long as the block has already been assigned to an article. All steps necessary for setting a block label are listed in the following:

  • Go to the Issue Viewer window
  • Move the mouse pointer over the block whose logical label shall be changed
  • Press the keyboard shortcut (see table in section 5) corresponding to the desired logical type so as to set it directly or follow the next steps
  • Click the right mouse button
  • Move the mouse pointer over the Label item from the newly-opened context menu
  • In the pop-up list containing all possible labels, move the mouse cursor over the desired label und press either the left of the right mouse button. Note that the logical labels which are incompatible to the physical type of the selected block are automatically disabled.
  • The logical label of the block is updated and the block visualization is refreshed so as to reflect this change

Deleting Multiple Blocks

It is possible to delete multiple blocks at once using a single extended shortcut (see also section 3.1.5). The precondition for this is that the blocks are adjacent to one another and can all be contained within an imaginary rectangle. The exact steps necessary are the following:

  • Go to the Issue Viewer window
  • Move the mouse pointer over to one of the corners of the desired rectangle
  • Press and hold the SHIFT key
  • Press and hold either mouse button
  • Drag the mouse to the opposite corner of the desired rectangle such that all blocks to be deleted are located within the bounds of the drawn rectangle
  • Release the mouse button and then the SHIFT key
  • All blocks located within the marked rectangular area are now discarded

Appending an Article to Another

In addition to appending single blocks to articles, the Korrektor also allows the appending of entire articles to other articles. In the latter case, all blocks of the source article will be transferred to the destination article. This operation can be accomplished as follows:

  • Go to the Issue Viewer window
  • Move the mouse pointer over one of the blocks belonging to the source article
  • Press and hold the CTRL key
  • Press and hold either mouse button
  • Drag the mouse pointer (with both the CTRL key and the mouse button pressed) over a block belonging to the destination article. Alternatively one may simply drag the mouse pointer on top of the text editor area in the main application window. For the latter to work correctly, the destination article must have already been opened in the Article Editor pane
  • Release the mouse button and then the CTRL key. The whole source article is now part of the destination article. The roof-, main- and subtitle of the source article are automatically relabeled as intermediary titles if the destination article already contains these elements

Opening an Article for Editing

This operation may be accomplished in several different ways:

  1. Via the Article View in the main application window:
  • Go to the main application window
  • Find the desired article from the list of articles in the Article View panel
  • Press the left mouse button over the found article. The whole article is now shown below in the Article Editor and can be further modified there
  1. Via the context menu in the Issue Viewer window:
  • Go to the Issue Viewer window
  • Move the mouse pointer over a block belonging to the article which shall be edited
  • Press the right mouse button
  • Choose the item Edit Article from the newly-opened context menu
  • The text of the selected block is now shown in the Article Editor and can be inspected and modified there
  1. Via a CTRL key press in the Issue Viewer window:
  • Go to the Issue Viewer window
  • Press and hold the CTRL key
  • While holding the CTRL key pressed, click the left mouse button over a block belonging to the desired article
  • The text of the whole article is now shown in the Article Editor and can be inspected and modified there
  1. Via the “Edit Article …” button from the main Korrektor application window (only possible when at least one block of the desired article has already been opened for editing):
  • Go to the main application window
  • Move the mouse over the “Edit Article …” button
  • Left mouse click on the button
  • The text of the whole article to which the block belongs is now shown in the Article Editor and can be inspected and modified there

Correcting Word Errors

Word spelling errors can be corrected using the text editor. In order to be able to do this one must first open a text block (or an entire article) for editing (see section ). The Word Highlighter window facilitates the correction of words by always showing the document page area centered around the word where the editing cursor is located. Additionally, the current word is highlighted using a red semi-transparent box. It is important to note that it is explicitly not allowed to delete entire words or the white spaces between words. The reasoning for this is explained in section , subsection Word correction tool.

Correcting Overlapping Blocks

It is generally possible that a few blocks partially overlap, as well as smaller blocks completely contained into larger ones. There exist several possibilities to correct such situations:

  • Via the Merge Blocks function: In the Issue Viewer window, draw a selection rectangle around all relevant blocks and select this option from the opened context menu. As a result, all selected blocks will be merged and their text lines will automatically be re-arranged in reading order.
  • In particularly unclear cases, it may be advantageous to simply delete all relevant blocks and manually create one (or more) block(s) instead. Note that the text of the deleted blocks will be retained by the Korrektor invisibly and will afterwards be correctly transferred to the newly-created blocks.
  • It is very important to note that simply deleting a block which is located on top of or completely within another one will not automatically transfer its text to the latter block. The text is only correctly transferred upon creating a new block or when modifying the existing “background” block.

Keyboard Shortcuts

Key Function
Label
r Set label ”Roof title“
t Set label ”Title“
s Set label ”Subtitle“
y Set label ”Byline“
l Set label ”Lead“
b Set label ”Body“
i Set label ”Intermediate title“
f Set label ”Footnote“
Type
CTRL+1 Set type ”Text“
CTRL+2 Set type ”Graphic“
CTRL+3 Set type ”Picture“
CTRL+4 Set type ”Table“
Categories
F1-F12 Set category 1 to 12
SHIFT+F1-F12 Set category 13 to 24
CTRL+F1-F12 Set category 25 to 36
Blocks
Backspace Remove from article
SHIFT+Backspace Remove
CTRL+a Create new article
< Change block reading order
> Change block reading order
View
+ Increase zoom factor by 10%
- Decrease zoom factor by 10%
w Show full page width
h Show full page height
Space Toggle block information view
Application
CTRL+s Save document
CTRL+z Undo
CTRL+y Redo
CTRL+f Search for block/article/page