> using embedded color profiles when displaying images - Preview and Xee display photos differently,

There are various problems with this, not least that I'm not very knowledgable about this. Basically, I'd like to have the program store the exact bitmap data that appears in the file, so as not to cause changes in the data when saving. However, when drawing with OpenGL it's not easy to apply colour adjustments on the fly, either. Possibly one could use pixel shaders for this, but my Mac mini doesn't support them, so I can't really do anything about it.

If anyone wants to help out with this, it would be appreciated.

> an option to turn off chaning the position/size of the window automatically when switching to next/previous image,

This option already exists.

> an option to center the window on screen (maybe just horizontally), instead of centering with respect to previous position, as I think it currently does,

This would be easy enough to add.

> when I select "next frame" from toolbar, and frame sizes are different, the window size does not change, but when I select the same command from the menu, it does, so it looks like a bug,

Not a bug, intentional (and can be changed via the option mentioned above). Changing the position and size of a window after clicking on a button in a window is really annoying, is why.

> a option to change window background color

The black border around the image, or the background on transparent images? The first might be a good idea. For the second, Xee tries to figure out what background colour the image has specified (but not all images do). So at the most, I could add an option to give a default background colour for those that don't have one.