Just a quick suggestion.  I was attempting to reproduce my shadow from ShadowFX in the Shadows configuration area of Curtains.  But unlike ShadowFX, the changes do not immediately appear, and instead, you have to click the "Apply changes" button every time.  That's understandable, but I was surprised there isn't an accelerator key so I can make changes with one hand on the mouse, and press a keyboard shortcut (like Alt-A, or Alt-P) to apply the changes with the other hand, and thereby get instant feedback on what I'm doing.  Instead, you're forced to guess from the preview, or go back and forth from the configuration to clicking the apply button, over and over.

Some of the other buttons could probably use accelerators as well, but that might be too much work for v1.  Regardless, I'm having fun trying this out .