[Fixed] No mouse pointer when there are unconnected network slots

[tomreyn]

When you attempt to start a game with network slots where some network slots are still unconnected, a message saying so is displayed. You need to confirm this message by clicking on 'OK'. However, on the screen displaying this message, there is no mouse pointer, so it's hard to click the OK button (pressing Enter does not work either).

[silnarm]

should be fixed now that widget_invert is merged into master, though we've lost the custom cursors . . .