Comment 85 for bug 187313

(Hopefully my description is not too confusing...sorry...I try to explain it as clearly and concisely as possible)

I experience something similar, but the behavior and the bug is as follows. By default the context menu when it is displayed, will "drop down" (to use a Windows' term), to the right of the link (or area) you have clicked in the browser. However if the length of the drop down is too long to be displayed as a "drop down", and there is sufficient space to display it as a "drop up" then it will drop up instead, that is, it will display to right of and above the link. (This, so far, is correct behavior). If horizontally the right click occurs in the middle of the page, this is not a problem. However, if the link is on the right side of the page, then when the user up clicks the right button (mouse right button up event) during a "drop up" display , then the hot spot of the mouse cursor will be over the bottom most selection of the context menu. As a result , this selection in the context menu will execute and the context menu will close. (The correct behavior is that the context menu should open, stay open, and await the next mouse click.)

Thus in summary, if one has a relatively long context menu and right clicks in the lower right part of the web page, then the last (or some other lower) item in the context menu executes, rather than the context menu getting displayed.

(Ubuntu Firefox 3.0 Beta 5).