DrawPreviewTexture -- any way to clip it?

The topic pretty much sums it up. I had this:

GUI.BeginGroup(rect);
GUI.DrawTexture(drawRect, tex);
GUI.EndGroup();

Everything was fine, but in order to support materials I switched to EditorGUI.DrawPreviewTexture instead of GUI.DrawTexture. Unfortunately now the drawing is no longer clipped by the BeginGroup. Intentional? Bug? Any work-arounds?

P.S. Using DrawPreviewTexture(drawRect, tex) works fine -- it gets clipped. It's only no longer clipped when I add the Material property -- DrawPreviewTexture(drawRect, tex, mat);

 

Just stumbled upon the same problem. I have a custom shader for previewing a texture and needed to use DrawPreviewTexture to have it draw with my custom shader in a custom material.

The solution is to look at the shader "Internal-GUITextureClip.shader" from the builtin shaders package (download link can be found on the unity download page). It has some additional properties that need to be utilized to properly clip the output:

sampler2D _GUIClipTexture;
uniform float4x4 unity_GUIClipTextureMatrix;

Take a look at the internal shader, which is really simple, to integrate it into your own shader (or directly utilize the internal shader in your material for DrawPreviewTexture).