is there a way to find out the level of transparency in a png?

Subject says it.  I'm working with gimp on tilesets for my next ks level, which uses further modifications of those I used in White City and Vague Feeling.  I've got a finished tileset that I don't want to modify, but I can't seem to match the transparency level on it with a second and third tileset I'm making to compliment it.  I always seem a few shades off.

I'm not a big fan of GIMP but if someone is and knows an easy GIMP-related solution to this, fine, but in this I'd suggest using Paint.NET as you could simply use the color picker tool on whatever transparent color you want to copy and it would give you and let you work with the the transparent color in it's particular alpha setting.

Ok, that is a good solution.  I've used paint.net before, but for some reason its layout didn't jive with me.  I'll try it for this problem though.  Thanks!

EDIT:  grrr.... yeah, I can't figure out how to do anything with paint.net.  I should be able to select all the tiles I want, delete them, then re-fill with the correct transparency and color.  I'm just using single colored transparent tiles cut into various shapes.  Instead, it deletes the marque selection.   

I'll keep trying, but if anyone has another suggestion, please let me know. 

Och... i want to help you and I'm very good at GIMP, but I'm not very good at English, so I don't understand 100% of the problem...

Ok, that is a good solution.  I've used paint.net before, but for some reason its layout didn't jive with me.  I'll try it for this problem though.  Thanks!

EDIT:  grrr.... yeah, I can't figure out how to do anything with paint.net.  I should be able to select all the tiles I want, delete them, then re-fill with the correct transparency and color.  I'm just using single colored transparent tiles cut into various shapes.  Instead, it deletes the marque selection.   

I'll keep trying, but if anyone has another suggestion, please let me know. 

Why even select them? Just use the fill tool on all the wrongly colored stuff. Just pick the fill tool, set the tolerance to zero, set blending to overwrite, then just shift-fill in.

If you want I could just fix up the tilesets for you. Wouldn't be a problem.

To answer your original question: In Gimp, hold shift when you left click with the color picker tool. An info window will appear that tells you everything about that color including the alpha.

Yeah!  That works!  Thank you sir!