ntextBindings(3) Alternative Bindings for the Text Widget

SYNOPSIS

package require Tcl 8.5

package require Tk 8.5

package require ntext ?0.81?




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.
  • The End key implements "Smart End" (successive keypresses move the cursor to the end of the display line, then to the end of the logical line); the Home key implements "Smart Home" (which is similar to "Smart End", but also toggles between the beginning and end of leading whitespace).
  • When a selection exists, a <<Paste>> operation (e.g. <Control-v>) overwrites the selection (as most editors do), and does so on all platforms.
  • 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.
  • 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").

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::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.

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}

KEYWORDS

bindtags, text

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