OK, now it makes sense why you were getting different results than I expected with the lasso tool earlier. RWPaint has lasso selection and normal lasso that is for drawing. The lasso selection really works exactly as Photoshop lasso - the graying out is how selection is visualized in RWPaint (instead of the marching ants) - I would recommend you to watch the image selections tutorial and it should become clear.
To get rid of the fading (selection) press ESC, or Undo.
To accomplish what you described, you probably should do this:
- select region that will be replaced with lasso
- press Delete - this will make a hole in the image
- press Ctrl+V to paste whatever you want to put into that hole (or drag and drop an image on the canvas)
- make sure the Paint under blending mode is active - this places the pasted image under the main image
- move the pasted selection into place and scale it (enable "Preserve aspect ratio" in the drawing tool configuration panel if you wish)
True, there is no direct "paste into selection" command, but step #5 should not take more than 5 seconds and I presume you would usually want to scale/position/rotate the pasted image anyway.
If you want, I can create a tutorial that demonstrates this - though I would need some sample images - preferably the unprocessed image and then the expected result.
RWPaint is much younger than PSP, but I bet it can do most of what PSP can do and sometimes more. But it works differently. It is not a 1:1 copy of Photoshop nor is its goal to become one. Creating yet another a copy of Photoshop would be pointless.