ntextBindings - Alternative Bindings for the Text Widget

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# ntextBindings(n) 1.0 tklib "Alternative Bindings for the Text Widget"

## Name

ntextBindings - Alternative Bindings for the Text Widget

## Synopsis

- package require Tcl 8.5
- package require Tk 8.5
- package require ntext ?1.0?

## Description

The ntext package provides a binding tag named Ntext for use by text widgets in place of the default Text binding tag.

The Text binding tag provides around one hundred bindings to the text widget (the exact number is platform-dependent). A few of these behave in a way that is different from most contemporary text-editing applications. Ntext aims to provide more familiar behaviour.

Features of the Ntext bindings that differ from the default Text bindings:

- Clicking near the end of a (logical) line moves the cursor to the end of that line (not the start of the next line). If the widget is in -wrap word mode, the same rule applies to display lines.

- Double-clicking or dragging near the end of a (logical) line will highlight/select characters from the end of that line (not the next line, or the region at the end of the line where there are no characters). If the widget is in -wrap word mode, the same rule applies to display lines.

- On windowing systems other than macOS Aqua, the Home key implements "Smart Home" (successive keypresses move the cursor to the start of the display line, then to the first non-whitespace character at the start of the logical line, then toggles between the beginning and end of leading whitespace); the End key implements "Smart End" (which is similar to "Smart Home"). On macOS Aqua, this functionality is provided by the operations <Command-Left> and <Command-Right>.

- When a selection exists, a "Paste" operation (e.g. <Control-v>) overwrites the selection (as most editors do), and does so on all platforms.

- On windowing systems other than macOS Aqua, the Insert key toggles between "Insert" and "Overwrite" modes for keyboard input. (In contrast, the Text binding tag uses Insert as a method to paste the "primary selection", a task that can be accomplished instead by mouse middle-click.)

- The Escape key clears the selection.

- On the macOS Aqua windowing system, Ntext follows Aqua conventions for keyboard navigation. Certain bindings related to vertical scrolling can be forced to behave in the same way as for the Windows and X11 windowing systems, by setting ::ntext::classicParagraphs to 1 (see Section CONFIGURATION OPTIONS).

- On the macOS Aqua windowing system, Ntext follows Aqua conventions for placement of the insert mark when keyboard navigation cancels a selection. This behavior can be switched off by setting ::ntext::classicSelection to 1 (see Section CONFIGURATION OPTIONS).

- Selecting with <Shift-Button1> selects from the previous position of the insertion cursor. (In the Text binding tag, the selection anchor may be the position of the previous mouse click.)

- <Shift-Button1> operations do not alter the selection anchor. (In the Text binding tag, they do.)

- By default, the Ntext binding tag does not provide several of the Control-key bindings supplied by the Text binding tag. Modern keyboards offer alternatives, such as cursor keys for navigation; modern applications often use the Control-key bindings for other purposes (e.g. <Control-p> for "print").

In the last three cases, the behavior of Text is often useful, so Ntext gives you the option of retaining it, by setting variables defined in the ::ntext namespace to 1 (instead of their default 0). Explaining these features in more detail:

- If the mouse is clicked at position A, then the keyboard is used to move the cursor to B, then shift is held down, and the mouse is clicked at C: the Text binding tag gives a selection from A to C; the Ntext gives a selection from B to C. If you want Ntext to behave like Text in this respect, set ::ntext::classicMouseSelect to 1.

- The Text binding tag allows successive <Shift-Button-1> events to change both ends of the selection, by moving the selection anchor to the end of the selection furthest from the mouse click. Instead, the Ntext binding tag fixes the anchor, and multiple Shift-Button-1 events can only move the non-anchored end of the selection. If you want Ntext to behave like Text in this respect, set ::ntext::classicAnchor to 1. In both Text and Ntext, keyboard navigation with the Shift key held down alters the selection and keeps the selection anchor fixed.

- The following "extra" Text bindings are switched off by default, but can be activated in Ntext by setting ::ntext::classicExtras to 1: <Control-a>, <Control-b>, <Control-d>, <Control-e>, <Control-f>, <Control-h>, <Control-i>, <Control-k>, <Control-n>, <Control-o>, <Control-p>, <Control-t>, <Control-space>, <Control-Shift-space>.

## CONFIGURATION OPTIONS

Ntext provides alternatives to a number of behaviours of the classic Text binding tag. Where there is an option, the Ntext behaviour is switched on by default, except for display-line indentation which is discussed on a separate page at ntextIndent.

The behaviour of Ntext may be configured application-wide by setting the values of a number of namespace variables:

::ntext::classicAnchor

- 0 - (default value) selects Ntext behaviour, i.e. the anchor point is fixed

- 1 - selects classic Text behaviour, i.e. the anchor point is variable

::ntext::classicExtras

- 0 - (default value) selects Ntext behaviour, i.e. several "extra" Text bindings are de-activated

- 1 - selects classic Text behaviour, i.e. the "extra" Text bindings are activated

::ntext::classicMouseSelect

- 0 - (default value) selects Ntext behaviour, i.e. the anchor point for mouse selection operations is moved by keyboard navigation

- 1 - selects classic Text behaviour

::ntext::classicParagraphs

- 0 - (default value) on macOS Aqua, certain keyboard bindings are made to behave in the same way as the Mac application TextEdit. The bindings involve vertical scrolling of the screen and are <?Shift-?Option-(Up|Down)>.

- 1 - on macOS Aqua, certain keyboard bindings are made to behave in the same way as for the Windows and X11 windowing systems and the classic Text, ignoring the conventions of Aqua. The bindings involve vertical scrolling of the screen and are <?Shift-?Option-(Up|Down)>.

::ntext::classicSelection

- 0 - (default value on macOS Aqua) selects Mac-like behaviour, i.e. when a navigation keystroke cancels a selection, the insert mark first moves to the end of the selection determined by the navigation direction of the keystroke, and then the keystroke is applied.

- 1 - (default value except on macOS Aqua) selects PC-like behaviour (the same as classic Text), i.e. when a navigation keystroke cancels a selection, the insert mark is not moved before the keystroke is applied.

::ntext::overwrite

- 0 - (initial value) text typed at the keyboard is inserted into the widget

- 1 - text typed at the keyboard overwrites text already in the widget

- The value is toggled by the Insert key.

::ntext::useBlockCursor

- 0 - the block cursor will not be used. When the widget is in overwrite mode (see ::ntext::overwrite), the ordinary cursor will change color instead.

- 1 - the block cursor will be used when the widget is in overwrite mode (see ::ntext::overwrite).

- The default value depends on the version of Tk. In versions of Tk earlier than 8.5.12, the sizing of the block cursor had a bug, and ::ntext::useBlockCursor defaults to 0. From 8.5.12 onwards the bug is fixed, and ::ntext::useBlockCursor defaults to 1.

## INTERNALS

In order to remain independent of the version of Tk (8.5 or 8.6), ntext defines its own virtual events. These new virtual events are used only in the Ntext binding tag, and therefore do not interfere with the real or virtual events used in other code.

These events include <<NtextCut>>, <<NtextCopy>>, <<NtextPaste>> which are used in place of <<Cut>>, <<Copy>>, <<Paste>> respectively.

The definition of the virtual event <<NtextCut>> (etc) is similar to that of <<Cut>> (etc) in Tk 8.6.

## BUGS

This version of ntext is intended to be compatible with all releases of Tk 8.5 and 8.6, and with the branches core-8-5-branch, core-8-6-branch, and trunk in the source code repository for Tk. Any incompatibility with any of these versions, for any Tk windowing system, should be reported as a bug. Please report such in the category ntext of the Tklib Trackers.

## EXAMPLE

To use Ntext but keep classic Text 's variable-anchor feature:

    package require ntext
    text .t
    set ::ntext::classicAnchor 1
    bindtags .t {.t Ntext . all}

## See Also

bindtags, ntext, ntextIndent, text

## Keywords

bindtags, text