How does one use onmousedown/onmouseup correctly?

Question

Whenever I write mouse handling code, the onmousedown/onmouseup/onmousemove model always seemed to force me to produce unnecessarily complex code that would still end up causing all sorts of UI bugs.

The main problem which I see even in major pieces of software these days is the "ghost mouse" event where you drag to outside the window and then let go. Once you return back into the window, the application still thinks you have the mouse down even though the button is up. This is especially annoying when you're trying to highlight something that goes to the border of the screen.

Is there a RIGHT way to write mouse code or is the entire model just flawed?

Answer 1

Ordinarily one captures the mouse events on mouse down so the mouse move and mouse up go through your code regardless of the caret moving out of you application window.

More recently this is a problem when running a VM or remote session, its difficult for apps in these to track the mouse outside of the machine screen area represented by a window on a host.

Answer 2

I'm not sure what environment you're attempting to track mouse buttons in, but the best way to handle this is to have a mouse listener that tracks onmouseup 100% of the time after you've detected onmousedown.

That way, it doesn't matter what screen region the user releases the mouse button in. It will reset no matter where it happens.