We require a C compiler supporting C99 now. The main purpose of
these fallbacks was for MSVC. From what I can see this is now all supported
by MSVC 2015+ anyway.
The only other change this includes is to replace isnanf() with the
(type infering) C99 isnan() macro, because MSVC doesn't provide isnanf().
This patch makes that work using 1 of 2 options:
1. Add all missing enums to the switch statement
or
2. Cast the switch argument to a uint to avoid having to do that (mostly
for GdkEventType).
I even found a bug while doing that: clearing a GtkImage with a surface
did not notify thae surface property.
The reason for enabling this flag even though it is tedious at times is
that it is very useful when adding values to an enum, because it makes
GTK immediately warn about all the switch statements where this enum is
relevant.
And I expect changes to enums to be frequent during the GTK4 development
cycle.
When decelerating the kinetic scroll, we can get into a position where it
looks like we are stuttering. This happens because the amount we move is
so little that it takes multiple frames to make forward progress by one
pixel.
This prevents that by detecting when we have reached the slow stutter of
the deceleration and simply stops the deceleration phase immediately.
https://bugzilla.gnome.org/show_bug.cgi?id=765493
GtkKineticScrolling implements the actual physics laws for friction
and springs. When created, position/velocity/boundaries/constants are
given, so at every gtk_kinetic_scrolling_tick() it returns the current
position, and whether the system is in rest.
https://bugzilla.gnome.org/show_bug.cgi?id=729608
