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1 | '\" |
2 | '\" Copyright (c) 1990-1994 The Regents of the University of California. | |
3 | '\" Copyright (c) 1994-1996 Sun Microsystems, Inc. | |
4 | '\" | |
5 | '\" See the file "license.terms" for information on usage and redistribution | |
6 | '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. | |
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8 | '\" RCS: @(#) $Id: focus.n,v 1.2.26.1 2004/10/28 10:19:29 dkf Exp $ | |
9 | '\" | |
10 | '\" The definitions below are for supplemental macros used in Tcl/Tk | |
11 | '\" manual entries. | |
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13 | '\" .AP type name in/out ?indent? | |
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38 | '\" .VS ?version? ?br? | |
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62 | '\" .OP cmdName dbName dbClass | |
63 | '\" Start of description of a specific option. cmdName gives the | |
64 | '\" option's name as specified in the class command, dbName gives | |
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71 | '\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $ | |
72 | '\" | |
73 | '\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages. | |
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77 | '\" # Start an argument description | |
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108 | .AS Tcl_Interp Tcl_CreateInterp in/out | |
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206 | '\" # SO - start of list of standard options | |
207 | .de SO | |
208 | .SH "STANDARD OPTIONS" | |
209 | .LP | |
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211 | .ta 5.5c 11c | |
212 | .ft B | |
213 | .. | |
214 | '\" # SE - end of list of standard options | |
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218 | .LP | |
219 | See the \\fBoptions\\fR manual entry for details on the standard options. | |
220 | .. | |
221 | '\" # OP - start of full description for a single option | |
222 | .de OP | |
223 | .LP | |
224 | .nf | |
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226 | Command-Line Name: \\fB\\$1\\fR | |
227 | Database Name: \\fB\\$2\\fR | |
228 | Database Class: \\fB\\$3\\fR | |
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242 | .. | |
243 | .de UL | |
244 | \\$1\l'|0\(ul'\\$2 | |
245 | .. | |
246 | .TH focus n 4.0 Tk "Tk Built-In Commands" | |
247 | .BS | |
248 | '\" Note: do not modify the .SH NAME line immediately below! | |
249 | .SH NAME | |
250 | focus \- Manage the input focus | |
251 | .SH SYNOPSIS | |
252 | .nf | |
253 | \fBfocus\fR | |
254 | \fBfocus \fIwindow\fR | |
255 | \fBfocus \fIoption\fR ?\fIarg arg ...\fR? | |
256 | .fi | |
257 | .BE | |
258 | ||
259 | .SH DESCRIPTION | |
260 | .PP | |
261 | The \fBfocus\fR command is used to manage the Tk input focus. | |
262 | At any given time, one window on each display is designated as | |
263 | the \fIfocus window\fR; any key press or key release events for the | |
264 | display are sent to that window. | |
265 | It is normally up to the window manager to redirect the focus among the | |
266 | top-level windows of a display. For example, some window managers | |
267 | automatically set the input focus to a top-level window whenever | |
268 | the mouse enters it; others redirect the input focus only when | |
269 | the user clicks on a window. | |
270 | Usually the window manager will set the focus | |
271 | only to top-level windows, leaving it up to the application to | |
272 | redirect the focus among the children of the top-level. | |
273 | .PP | |
274 | Tk remembers one focus window for each top-level (the most recent | |
275 | descendant of that top-level to receive the focus); when the window | |
276 | manager gives the focus | |
277 | to a top-level, Tk automatically redirects it to the remembered | |
278 | window. Within a top-level Tk uses an \fIexplicit\fR focus model | |
279 | by default. Moving the mouse within a top-level does not normally | |
280 | change the focus; the focus changes only when a widget | |
281 | decides explicitly to claim the focus (e.g., because of a button | |
282 | click), or when the user types a key such as Tab that moves the | |
283 | focus. | |
284 | .PP | |
285 | The Tcl procedure \fBtk_focusFollowsMouse\fR may be invoked to | |
286 | create an \fIimplicit\fR focus model: it reconfigures Tk so that | |
287 | the focus is set to a window whenever the mouse enters it. | |
288 | The Tcl procedures \fBtk_focusNext\fR and \fBtk_focusPrev\fR | |
289 | implement a focus order among the windows of a top-level; they | |
290 | are used in the default bindings for Tab and Shift-Tab, among other | |
291 | things. | |
292 | .PP | |
293 | The \fBfocus\fR command can take any of the following forms: | |
294 | .TP | |
295 | \fBfocus\fR | |
296 | Returns the path name of the focus window on the display containing | |
297 | the application's main window, or an empty string if no window in | |
298 | this application has the focus on that display. Note: it is | |
299 | better to specify the display explicitly using \fB\-displayof\fR | |
300 | (see below) so that the code will work in applications using multiple | |
301 | displays. | |
302 | .TP | |
303 | \fBfocus \fIwindow\fR | |
304 | If the application currently has the input focus on \fIwindow\fR's | |
305 | display, this command resets the input focus for \fIwindow\fR's display | |
306 | to \fIwindow\fR and returns an empty string. | |
307 | If the application doesn't currently have the input focus on | |
308 | \fIwindow\fR's display, \fIwindow\fR will be remembered as the focus | |
309 | for its top-level; the next time the focus arrives at the top-level, | |
310 | Tk will redirect it to \fIwindow\fR. | |
311 | If \fIwindow\fR is an empty string then the command does nothing. | |
312 | .TP | |
313 | \fBfocus \-displayof\fR \fIwindow\fR | |
314 | Returns the name of the focus window on the display containing \fIwindow\fR. | |
315 | If the focus window for \fIwindow\fR's display isn't in this | |
316 | application, the return value is an empty string. | |
317 | .TP | |
318 | \fBfocus \-force \fIwindow\fR | |
319 | Sets the focus of \fIwindow\fR's display to \fIwindow\fR, even if | |
320 | the application doesn't currently have the input focus for the display. | |
321 | This command should be used sparingly, if at all. | |
322 | In normal usage, an application should not claim the focus for | |
323 | itself; instead, it should wait for the window manager to give it | |
324 | the focus. | |
325 | If \fIwindow\fR is an empty string then the command does nothing. | |
326 | .TP | |
327 | \fBfocus \-lastfor\fR \fIwindow\fR | |
328 | Returns the name of the most recent window to have the input focus | |
329 | among all the windows in the same top-level as \fIwindow\fR. | |
330 | If no window in that top-level has ever had the input focus, or | |
331 | if the most recent focus window has been deleted, then the name | |
332 | of the top-level is returned. The return value is the window that | |
333 | will receive the input focus the next time the window manager gives | |
334 | the focus to the top-level. | |
335 | .SH "QUIRKS" | |
336 | .PP | |
337 | When an internal window receives the input focus, Tk doesn't actually | |
338 | set the X focus to that window; as far as X is concerned, the focus | |
339 | will stay on the top-level window containing the window with the focus. | |
340 | However, Tk generates FocusIn and FocusOut events just as if the X | |
341 | focus were on the internal window. This approach gets around a | |
342 | number of problems that would occur if the X focus were actually moved; | |
343 | the fact that the X focus is on the top-level is invisible unless | |
344 | you use C code to query the X server directly. | |
345 | .SH "EXAMPLE" | |
346 | To make a window that only participates in the focus traversal ring | |
347 | when a variable is set, add the following bindings to the widgets | |
348 | \fIbefore\fR and \fIafter\fR it in that focus ring: | |
349 | .CS | |
350 | button .before -text "Before" | |
351 | button .middle -text "Middle" | |
352 | button .after -text "After" | |
353 | checkbutton .flag -variable traverseToMiddle -takefocus 0 | |
354 | pack .flag -side left | |
355 | pack .before .middle .after | |
356 | bind .before <Tab> { | |
357 | if {!$traverseToMiddle} { | |
358 | \fBfocus\fR .after | |
359 | break | |
360 | } | |
361 | } | |
362 | bind .after <Shift-Tab> { | |
363 | if {!$traverseToMiddle} { | |
364 | \fBfocus\fR .before | |
365 | break | |
366 | } | |
367 | } | |
368 | \fBfocus\fR .before | |
369 | .CE | |
370 | ||
371 | .SH KEYWORDS | |
372 | events, focus, keyboard, top-level, window manager |