How are you getting the tooltip to stay on screen after clicking on the taskbar? The only way I can get a tooltip for collapsed code in EmEditor is to hover over sections in the outline plugin... and the only way to keep the tooltip from disappearing when I move the mouse away is to right-click. Even if I am able to get another application open/active without the tooltip disappearing -- the tooltip is underneath the newly activated window, not on top.

Compare that to Opera 10/11, where if a window like Total Commander is on top of an Opera Window - the Opera tooltips (e.g. Yahoo Mail) get activated all the time and show inside the TC window. This is all due to Opera using proprietary GUI controls that don't respect MS-Windows rules.