Run SwingSet. Choose "Menus & Toolbars". Click on any menu in the menu bar to pull it downu. Click in another unrelated window while the menu is down. The other window will activate, but the menu will remain down. Moving the mouse over the menu bar in the "inactive" window will pull down other menus.

On Solaris, this has the additional effect of leaving a "floating" the menu above an unrelated window, if that window happens to overlap as it activates.
To see this, run on Solaris and resize the SwingSet window to about 650x425. Activate another unrelated window (call it "window a") and move it so that it covers the Junk Food menu in the SwingSet window. Activate SwingSet again by clicking in its title bar. Click on Junk Food to pull down that menu. Click in window a to activate it and bring it to the top. Note Junk Food menu floating above window a.