evnt_multi() sometimes ignores mouse clicks

Under some circumstances, evnt_multi() with flags of MU_KEYBD|MU_BUTTON|MU_TIMER & a time of zero does not return the button status when the left button is clicked.
How to reproduce:
. save the desktop with an open window showing the folder where the test program is located
. reboot
. before opening a dialog or dropping down a menu, launch the program from the open window
. left clicks are ignored.

Opening a dialog before running the program bypasses this bug.

See the attached sample program.