TIP 84: Add control for mouse movement filtering

Author:         Jyrki Alakuijala <[email protected]>
Author:         Jeff Hobbs <[email protected]>
State:          Final
Type:           Project
Vote:           Done
Created:        26-Feb-2002
Tcl-Version:    8.4
Tk-Ticket:      564642


When the mouse is moved, the Tcl/Tk system eats most of the mouse movement events and only the last movement event when Tcl/Tk is not busy is stored in the event queue. I would like to obtain all the movement events from the X-server or the Windows UI.


I have an artistic drawing program where I need to track mouse as accurately as possible. At the moment I poll the XQueryPointer() in the busy loops to create (pseudo)events in the C-side of the code to compensate for the missing events, but (of course) this does not work in Windows.

I would like to have an option for the widget system or for the window control so that a window (or, alternatively all the windows) could receive all the movement events instead of only the last buffered one.

This has been a problem for me since 1995 and has - at many times - caused me to consider changing the widget system.


    int Tk_CollapseMotionEvents(Display *display, int collapse)

A reference implementation is SF Tk patch 564642, which adds a flag to the TkDisplay that specifies whether motions events should be collapsed or not. The default is the current behavior of collapsing these events.


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