Is there any way to save or set transparency when saving to a tga file?

Example: import a photo, draw a shape on it, select both shape and photo, subtract shape, gives me a hole in the photo. Save as tga. Import the tga file back into Xara, the hole is white. I want it transparent.

This is easy with a png file, but I want to be able to do it with a tga file.

Reason for this: I want to modify a tga file that comes with Magix Movie Edit Pro/VPX and replace it. When the effect is used in the video editor, the image has transparency for part of it and I see the underlying video in the hole.

Thanks