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Diffstat (limited to 'doc/selection.n')
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diff --git a/doc/selection.n b/doc/selection.n index f5bb660..245a97f 100644 --- a/doc/selection.n +++ b/doc/selection.n @@ -140,6 +140,26 @@ If \fIcommand\fR is specified, it is a Tcl script to execute when some other window claims ownership of the selection away from \fIwindow\fR. \fISelection\fR defaults to PRIMARY. .RE +.SH WIDGET FACILITIES +.PP +The \fBtext\fR, \fBentry\fR, \fBttk::entry\fR, \fBlistbox\fR, \fBspinbox\fR and \fBttk::spinbox\fR widgets have the option \fB\-exportselection\fR. If a widget has this option set to boolean \fBtrue\fR, then (in an unsafe interpreter) a selection made in the widget is automatically written to the \fBPRIMARY\fR selection. +.PP +A GUI event, for example \fB<<PasteSelection>>\fR, can copy the \fBPRIMARY\fR selection to certain widgets. This copy is implemented by a widget binding to the event. The binding script makes appropriate calls to the \fBselection\fR command. +.PP +.SH PORTABILITY ISSUES +.PP +On X11, the \fBPRIMARY\fR selection is a system-wide feature of the X server, allowing communication between different processes that are X11 clients. +.PP +On Windows, the \fBPRIMARY\fR selection is not provided by the system, but only by Tk, and so it is shared only between windows of a master interpreter and its unsafe slave interpreters. It is not shared between interpreters in different processes or different threads. Each master interpreter has a separate \fBPRIMARY\fR selection that is shared only with its unsafe slaves. +.PP +.SH SECURITY +.PP +An unsafe interpreter cannot read from the \fBPRIMARY\fR selection because its \fBselection\fR command is hidden. For this reason the \fBPRIMARY\fR selection cannot be written to the Tk widgets of a safe interpreter. +.PP +A Tk widget can have its option \fB\-exportselection\fR set to boolean \fBtrue\fR, but in a safe interpreter this option has no effect: writing from the widget to the \fBPRIMARY\fR selection is disabled. +.PP +These are security features. A safe interpreter may run untrusted code, and it is a security risk if this untrusted code can read or write the \fBPRIMARY\fR selection used by other interpreters. +.PP .SH EXAMPLES .PP On X11 platforms, one of the standard selections available is the |