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Whenever the user changes the value of the scrollbar, the scrollbar’s callback is called (if one is associated with the scrollbar). The scrollbar position can be changed in several ways. The most simple one is to left-click on the knob of the scrollbar and move the know while the left mouse button is kept pressed down. Left-clicking beside the know will move the knob in large steps toward the current position of the mouse, clicking with the middle or right mouse button in smaller steps. Small shifts can also be obtained by clicking on one of the buttons at the side of the scrollbar or by using the scroll-wheel somehwere over the scrollbar.
You can control under which conditions the scrollbar gets returned to your application or its callback invoked. To change the default, call
void fl_set_object_return(FL_OBJECT *obj, unsigned int when);
where the parameter when
can be one of the following four
values:
FL_RETURN_NONE
Never return or invoke callback.
FL_RETURN_END_CHANGED
Return or invoke callback at end (mouse release) if value is changed (since last return).
FL_RETURN_CHANGED
Return or invoke callback whenever the scrollbar value is changed. This is the default.
FL_RETURN_END
Return or invoke callback at end (mouse release) regardless if the value is changed or not.
FL_RETURN_ALWAYS
Return or invoke callback whenever value changed or mouse button was released.
The default setting for when
for a scrollbar object is
FL_RETURN_CHANGED
(unless during the build of XForms you
set the configuration flag --enable-bwc-bs-hack
in which case
the default is FL_RETURN_NONE
to keep backward
compatibility with earlier releases of the library).
See demo program objreturn.c for an example use of this.
Next: Other Scrollbar Routines, Previous: Scrollbar Types, Up: Scrollbar Object [Contents][Index]