---
name: "persistentSelection"
section: "3tk"
platform: "linux"
package: "tklib"
version: "0.9-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/persistentSelection"
---

# persistentSelection(3tk)

Enhanced PRIMARY selection

```

```

## NAME

persistentSelection - Enhanced PRIMARY selection

## SYNOPSIS

package require **Tcl 8.5**

package require **Tk 8.5**

package require **persistentSelection ?1.0?**

**persistentSelection::fixText**

**persistentSelection::getClassicPrimarySel** ?*displayOf*? ?*withOthers*?

**persistentSelection::getPrimarySel** ?*displayOf*?

**persistentSelection::report** *type* *pathName*

```

```

## DESCRIPTION

Consider a **Tk** widget that sets its **-exportselection** option to boolean **true**, thereby exporting its selection.  When the selection in the widget is canceled, by default **Tk** also cancels the **PRIMARY** selection.  In this situation, an attempt to read the **PRIMARY** selection, e.g. by a **\<\<PasteSelection\>\>** event, will fail.

The **persistentSelection** package offers more convenient behavior.  It will sustain as the **PRIMARY** selection the last non-empty value set by any **Tk** widget that it monitors, as long as the **PRIMARY** selection is not claimed by another process, or by a widget that it does not monitor.

The **persistentSelection** package works by binding to the **\<\<Selection\>\>** event on the widgets of interest, and using this binding to monitor any change of the selection in the widget.  Its commands are confined to the namespace **::persistentSelection**.

## COMMANDS

- **persistentSelection::fixText**

  Call this command once to resolve problems with **text** widgets that use the default **Text** bindtag (rather than **Ntext**).  See **Text widgets** for an explanation.

  The command adjusts some **Text** bindings to generate **\<\<Selection\>\>** events; and it re-orders calls to the **text** widget **tag** command in the private command **::tk::TextSelectTo**, so that this command cooperates better with **persistentSelection**.

  These adjustments are needed only to older versions of **Tk**.  The command **persistentSelection::fixText** has no effect on sufficiently recent releases.  It can safely be called for any version of **Tk**.

- **persistentSelection::getClassicPrimarySel** ?*displayOf*? ?*withOthers*?

  - •

    *displayOf* - a **Tk** window path on the display to be interrogated (optional, default {**.**})

  - •

    *withOthers* - whether to return the **PRIMARY** selection if it is owned by another process or interpreter (optional, boolean, default **false**)

-

  A command to return the classic (non-persistent) form of the **PRIMARY** selection.  If the selection does not exist, or is sustained only by **persistentSelection**, the command returns the empty string.

- **persistentSelection::getPrimarySel** ?*displayOf*?

  - •

    *displayOf* - a **Tk** window on the display to be interrogated (optional, default {**.**})

-

  A command to return the value of the **PRIMARY** selection.  If the selection does not exist, the command returns the empty string.  The usual **Tk** commands are perfectly valid, but they raise an error if the selection does not exist.

- **persistentSelection::report** *type* *pathName*

  - •

    *type* - (value **text** or **entry**) classification of the widget whose selection has changed

  - •

    *pathName* - the **Tk** window path of the widget whose selection has changed

-

  To make package **persistentSelection** monitor a widget, this command must be bound to the **\<\<Selection\>\>** event on that widget.  The command records changes in the widget's selection, and uses the information to sustain a non-empty **PRIMARY** selection on each display.

## USAGE

### SCRIPT REQUIREMENTS

For each widget that will be monitored by **persistentSelection**, the command **persistentSelection::report** must be bound to event **\<\<Selection\>\>** in one of the widget's binding tags.

For example, the developer may wish to use **persistentSelection** with every **text** and **entryPlus** widget in an application: this can be achieved by adding the **\<\<Selection\>\>** binding to the **Text** and **EntryPlus** bindtags.  See **EXAMPLES**.

If **persistentSelection** is not required for all widgets of a particular class, the binding can be added to per-widget bindtags.  See **EXAMPLES**.

### WIDGET REQUIREMENTS

To be capable of being monitored by **persistentSelection**, a widget must satisfy three conditions:

- •

  It must have an **-exportselection** option that allows it to export its selection to the **PRIMARY** selection.

- •

  It must generate a **\<\<Selection\>\>** event whenever its selection changes.

- •

  its bindings to other events should be suitable - specifically, in versions of **Tk** older than **8.6.6**, a GUI event that extends or reduces the selection from one non-empty value to another should not use an intermediate state that has an empty selection, because this confuses **persistentStore**.

The **Tk** and **Ttk** widgets that can export their selection are **text**, **entry**, **listbox**, **spinbox**, **ttk::entry**, **ttk::spinbox**, and **ttk::combobox**.

### TEXT WIDGETS

In versions of **Tk** older than **8.6.9**, the **text** widget does not generate **\<\<Selection\>\>** events in a few "corner cases" in which its selection changes.  These omissions can be corrected by changes to the **Text** bindings, in order to satisfy the second condition of **Widget requirements**.

In addition, versions of **Tk** older than **8.6.6** process selection events slightly differently from newer versions, and in combination with the **Text** bindings this confuses **persistentStore**.  If an upgrade to the current version of **Tcl/Tk** is not feasible, this problem can be resolved by making a slight modification to the widget bindings, in order to satisfy the third condition of **Widget requirements**.

Either the script should call the command **persistentSelection::fixText** to adjust the **Text** bindings and the commands that they call; or the widget can use the **Ntext** binding tag (for **ntext** version 1.0 or above) instead of the default **Text** bindtag.

In either case, the argument *type* supplied to command **persistentSelection::report** should have the value **text**.

### ENTRY, SPINBOX, TTK::ENTRY, TTK::SPINBOX, AND TTK::COMBOBOX WIDGETS

The **entry**, **spinbox**, **ttk::entry**, **ttk::spinbox**, and **ttk::combobox** widgets do not generate a **\<\<Selection\>\>** event when their selection changes, and therefore require modification.

The package **widgetPlus** provides **snit** wrappers **widgetPlus::entryPlus**, **widgetPlus::spinboxPlus**, **widgetPlus::ttkEntryPlus**, **widgetPlus::ttkSpinboxPlus**, and **widgetPlus::ttkComboboxPlus** respectively.  Each **widgetPlus** widget generates the required **\<\<Selection\>\>** events.

In all these cases, the argument *type* supplied to command **persistentSelection::report** should have the value **entry**.  This argument determines how **persistentSelection** will inspect the widget's selection, and the commands that do so are the same for all these widgets.

### LISTBOX WIDGETS

A similar wrapper has not been created for the **listbox** widget, which has the complication of permitting multiple selections.

## TO DO

- •

  Test on a system with multiple displays.

## BUGS

This version of **persistentSelection** 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*, *revised\_text*, 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 *persistentSelection* of the *Tklib Trackers* \[http://core.tcl.tk/tklib/reportlist\].

## EXAMPLES

Each example uses **persistentSelection** to retain the last non-empty value of the selection in certain widgets.  Each example also includes the creation of sample widgets.

Monitor all **entryPlus** widgets.

```
package require widgetPlus
widgetPlus::entryPlus .ep
pack .ep
package require persistentSelection
bind EntryPlus <<Selection>> {::persistentSelection::report entry %W}
```

Monitor all **text** widgets that use the default **Text** bindings.

```
text .t
pack .t
package require persistentSelection
::persistentSelection::fixText
bind Text <<Selection>> {::persistentSelection::report text %W}
```

Monitor all **text** widgets that use the default **Text** bindings, and all **entryPlus** widgets.

```
text .t
pack .t
package require widgetPlus
widgetPlus::entryPlus .ep
pack .ep
package require persistentSelection
::persistentSelection::fixText
bind Text <<Selection>> {::persistentSelection::report text %W}
bind EntryPlus <<Selection>> {::persistentSelection::report entry %W}
```

Monitor all **text** widgets that use **Ntext** bindings.

```
text .t
pack .t
package require ntext
bindtags .t {.t Ntext . all}
package require persistentSelection
bind Ntext <<Selection>> {::persistentSelection::report text %W}
```

Monitor a single **entryPlus** widget **.ep**

```
package require widgetPlus
widgetPlus::entryPlus .ep
pack .ep
package require persistentSelection
bind .ep <<Selection>> {::persistentSelection::report entry %W}
```

Monitor a single **text** widget **.t**

```
text .t
pack .t
package require persistentSelection
bind .t <<Selection>> {::persistentSelection::report text %W}
```

## SEE ALSO

bindtags, ntext, text, widgetPlus