A bitmap fill can be applied by dragging a bitmap from the bitmap gallery or via explorer and dropping it onto a shape. Version 3.2 of Xtreme and Xtreme Pro require you to hold down the shift key when dropping a photo onto a shape to cause the bitmap to be applied as a fill.
The Photo is sized to just fill the visible shape. You can resize and rotate the image by dragging the ends of the fill arrow (the correct aspect-ratio now remains locked when you do this). You can push the picture around inside the shape by dragging on the center fill handle, anywhere on a fill arrow or by holding Shift and dragging anywhere on the photo.
If you hold Shift while dragging the ends of the fill arrow it will stretch / skew the bitmap. Holding Ctrl will constrain the angles.