GTK and Windows appear to handle timers very differently:

specifically, the elapsed time between calls varies much more with
GTK than it does under Windows. Therefore, I now take my own time
readings on every timer call, and this appears to have made the
animations run at closer to the same speed between platforms. Having
done that, I decided some of them were at the _wrong_ speed, and
fiddled with each game's timings as well.

[originally from svn r4189]

cube.c

@@ -160,7 +160,7 @@ enum {
 enum { LEFT, RIGHT, UP, DOWN, UP_LEFT, UP_RIGHT, DOWN_LEFT, DOWN_RIGHT };
 
 #define GRID_SCALE 48.0F
-#define ROLLTIME 0.1F
+#define ROLLTIME 0.13F
 
 #define SQ(x) ( (x) * (x) )