The image editor in Construct is really buggy. One thing it seems to have trouble with is deleting colors, or making things transparent. This makes importing images very difficult.
When I try to paste a sprite, and remove the green (or white, or other color) background, a lot of weird things happen.
For example, I'll try to set everything to 0 in order to make a transparent color. When I go to the paint bucket and try to fill the green areas to transparent, it fills everything except for a few spots on the outside and inside of the sprite. The previous color still remains except around the outline of the sprite.
Here, this will explain what I mean:
<img src="http://machriderx.googlepages.com/constructbug.gif">
See what I mean?
That wouldn't be so bad if I could just erase the green stuff on the outside (and inside).
In fact, that's what I've tried to do. I've tried both the magic wand and select color tool to select the nasty outside color residue and delete it. But, when I do that, it ends up just fading the color a bit and leaving a slightly less green outline on the outside or smudges the pixels as if it were doing some sort of anti-aliasing (even though there doesn't seem to be an option to turn this off).
I really hope this gets fixed soon, because it's really annoying.
Also, I would like to make a suggestion. I think it would be a good idea if Construct recognized PNG transparency. That way, the sprites I want to import could already have the correct transparencies rather than having me to remove all the transparency color junk myself.
Edit: By the way, if you want to try to reproduce this bug yourself, try importing this file into Construct (although from my experience, any sprite I try does the same thing):
http://machriderx.googlepages.com/triangle.bmp
And then set the color to 0,0,0,0 and use the paint bucket and see what happens.