Unable to continuously clicking on GtkButton

[Simon Chan <simon780 gmail com>]

Hi All,

    I have written a program which prints a line on the screen when a
button is pressed, just to test my own compiled GTK+ 2.18.1 Library.

    The problem is, I click my mouse on the button, it prints a
message. The second time I click on the exact same spot, it doesn't
work, the button is not even shown is was pressed!! Then I move the
mouse cursor for a pixel or two, the button can be pressed again.

    I thought this was strange. So I tried again with a bigger button,
and click on it continuously on the same spot, it worked!!!
But strange enough, when I clicked on near bottom edge of the button,
it stopped working, clicking anywhere above the lower "blocked" area,
it all worked.

All the following env variables are properly set.
  CPPFLAGS,LDFLAGS,PKG_CONFIG_PATH,LD_LIBRARY_PATH,PATH

When I run the program with system's GTK+, it works fine. I have also
tried with my compiled GTK+ 2.17, it suffered the same problem, does
anyone has any idea what could be the cause of this strange button
behavior?

Thx a lot!

Simon