Rectangular Masking for the HUD (/Canvas)

There doesn’t seem to be a function to mask/clip certain rectangular areas of the HUD. In old UE3 (UDK) there was a function named PushMaskRegion(), with which you could mask the HUD without a problem. Like so:

//draw various unmasked things
 Canvas->Canvas->PushMaskRegion(10,10, 100, 100);
//draw various masked things
//draw various unmasked things

Now that function seems to be deleted, though it is crucial for so many things like minimaps, health bars or scrollable areas. Could you please bring back that function? I need it very badly!

Thanks in advance