Fixed lost mouse button when in relative mouse warp mode and you click on the title bar, entering a modal move/resize loop. Testing: * Set the SDL_HINT_MOUSE_RELATIVE_MODE_WARP hint true, run testsprite2, press Ctrl-R to enter relative mode, alt tab away from the window, then click on the title bar of the window. Didn't get the mouse button release before, and we do now. CR: Yahn + Alfred