Normally, "shift", "ctrl" can be used with left mouse button when user see the viewpoint scene.

I noticed that If I applied MTSDrag to make an MTSInstance dragable. Things became wired and unpredictable when user see the 3d scene by pressing the "shift", "ctrl" or "Alt" by accident. 3D objects will rotate and scale in a mad manner.

What's the solution?

Thanks in advance!!!