Lost Mouse Events when using glutAttachMenu()

In my application, the right mouse button is connected to a pop-up menu (glutAttachMenu()) and the left button is processed by the standard mouse CB (glutMouseFunc()). My beta testers have complained about strange behavior associated with a specific order of button presses:

Left Down
Right Down
Left Up
Right Up

I have determined that when the menu is activated, the left button events get lost. Hence the Left Up event gets lost. There is no way I can check for this since as far as my application knows, the user simply never let go of the button.

It seems to me that this is a bug. I can certainly understand why the menu CB would trap mouse activity. But it shouldn’t discard events from buttons it isn’t processing. These should get queued up somehow.

Is there a patch for this? Any suggestions?