[fixed] Color slide hanging

[micheus]

In the official version it's crashing Wings3D.
In the current master branch with the workaround it is hanging Wings3D.
To reproduce use the 'Create Texture' - it always happens:
- select *Noise* and edit Options;
- click in Color1 and use the sliders to adjust the color;
- click in Color2 and use the sliders to adjust the color - still not hang;
- Click OK and close the Option dialog;
- Click OK and apply the shaders;
- Access the Create Texture again;
- edit the *Noise* Options;
- click in Color1 and now it will hang!!!

That was not present in v2.0.1