I'm using a laptop, connecting one or two external displays, - one using the HDMI port, second using an USB "dock station" (Toshiba standalone). Second screen normally to the right, third screen (usb) above the laptop screen. Often when I have disconnected the USB external display, my Firefox browser window are still "on the third display" - position as if this display was still active. Even if I quit Firefox and restarts ( or even restarts windows ) the same position window is retained. The only way to fix it (when the USB connected display is not available), is to change the window position of the second (HDMI) display to cover the area of the USB one, then move Firefox window to my main laptop display, and then reposition the second screen back to the normal. Normally, I expect applications to automatically reposition the windows to the available display(s) under the conditions that an extra display is removed. However, this seems not to happen with Firefox. It's inconvinient, but possible to fix with the second screen available, but I'm lost when I am not able to connect an external display ... Is there any solution to this? Is it possible to change (reset) window positions directly in RegEdit ??