GDK_POINTER_MOTION_HINT_MASK being ignored; why?

[Deborah Swayne <dfs research att com>]

When I test event->is_hint inside my motion_notify callback,
it's 0 even though I carefully execute

  gtk_widget_set_events (sp->da, GDK_EXPOSURE_MASK
             | GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK
             | GDK_POINTER_MOTION_MASK | GDK_POINTER_MOTION_HINT_MASK);

What might I be doing to nullify that setting?

I'm looking at my code as it's built using gtk+ 1.2.8 under irix 6.5.

Debby

-- 
Deborah Swayne               AT&T Labs - Research 
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