Подскажите как это правильно перевести. Особенно последнее предложение:
If you're hoping to make a temporary popup control in your window and want to use CS_DROPSHADOW to reinforce the fleeting nature of the popup, you can't use it with WS_CHILD -- it just ignores CS_DROPSHADOW. You'll need to make your control be WS_POPUP and then position it where you want it when it opens.