[racket-dev] mouse motion events in Linux

Hi Matthew,

On 07/16/2011 10:31 PM, Matthew Flatt wrote:
 > Short answer: change pushed.

Thanks for picking this up.

I see you also removed GDK_POINTER_MOTION_HINT_MASK , which
means we will be again seeing more motion events than before.

Please note that GDK_POINTER_MOTION_HINT_MASK is really orthogonal to
GDK_POINTER_MOTION_MASK / GDK_BUTTON_MOTION_MASK .

The latter selects in which cases motion events should be sent
(GDK_POINTER_MOTION_MASK == always, GDK_BUTTON_MOTION_MASK == only
when a mouse button is pressed).

The former enables coalescing of motion events so that the application
doesn't see so many of them. GDK_POINTER_MOTION_HINT_MASK by itself
doesn't enable the sending of motion events.

See also:
http://www.linuxtopia.org/online_books/gui_toolkit_guides/gtk+_gnome_application_development/sec-gdkevent_5.html

(Apology if you knew all this already).

Note that this page states that if the motion events can be handled quickly (under 5 ms),
then not using  GDK_POINTER_MOTION_HINT_MASK may be preferable.
I guess most apps don't do anything with the motion events which is probably
quite fast indeed.

Stephan