Argh, I was hoping you wouldn't say "Gimp" since this software is really complicated. ![Tongue :P](https://forum.solarus-games.org/en/Smileys/default/tongue.gif)
But it worked. In fact, when I opened the picutre on Gimp, the alpha channel was already set ! I saved the picture again, tried to lanch the game, and the switches worked well and had a transparent background. I suppose I can do the same operation with bushes.
Thanks for your explanations and your patience with my little problems.
![Tongue :P](https://forum.solarus-games.org/en/Smileys/default/tongue.gif)
But it worked. In fact, when I opened the picutre on Gimp, the alpha channel was already set ! I saved the picture again, tried to lanch the game, and the switches worked well and had a transparent background. I suppose I can do the same operation with bushes.
Thanks for your explanations and your patience with my little problems.
![Wink ;)](https://forum.solarus-games.org/en/Smileys/default/wink.gif)