How do I repaint after tooltip disappears?

I've created an applet which has one large panel to display data surrounded by several controls (buttons, textfields, etc.). The large panel contains several layers of labels which I render myself.

The controls all have tooltips associated with them, and some of these tooltips overlap the main panel. When they disappear, they leave a hole in the main panel image until the main panel is repainted.

Now mind you, this does not always happen. It only occurs when the cursor is in a certain range. If you get far enough to either the left or right (no difference noted for changes along the Y axis), the holes are painted over when the tooltip disappears.

I'm not well-versed on how tooltips and repainting are supposed to work, and if this is a sign that there's something dreadfully wrong with my program, but if I can just call repaint on the main panel whenever the tooltip disappears, I should be fine. Is there开发者_StackOverflow中文版 something I can override in tooltip to make this happen?

I'm using Swing

Thanks.

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To answer your question (after you found a solution by the comments): Swing has some quite elaborate repaint management built in. When a tooltip disappears, the rectangle below it is repainted.

Now, which components have to be repainted? All those who overlap with the given rectangle, and are not themselves hidden (in the region in question) by other components - but only opaque components count here. (This is the whole reason we need the opaque property on JComponent - to optimize repainting.)

Your label declared itself being opaque, but did not really paint its whole area on a paintComponent, and such the region of the tooltip which should have been covered by the label stayed unpainted.

Declaring your label to be partly transparent caused also the concerning region of the component behind it to be repainted.