#973 Crash after middle-clicking empty space in window tab bar

[AshyRaccoon]

I am using Construct 0.98.9

Steps to reproduce:
Make a new Direct-X game.
Middle click anywhere in the empty space on the bar to the right of the "Application 1 : Layout 1" tab.
This makes Construct crash for me.

It also works to load a cap, rather than making a new game. So long as the bar is present, and there is empty space to middle-click on.

I am using the Visual Studio 2008 theme.