I have been following a good tutorial about creating a Button skin that allows you to add different images:
http://brianackermann.wordpress.com/2010/05/06/flex-4-reusable-icon-button-skins/#expandSource
After a couple of minor changes it worked well, but when I use the same class, skin & images in another project the images always look blended or transparent. I have tried adjusting image blendmode settings and alpha in the skin, app and stylesheet.
The 2 green images should match, as should the white ones. The buttons are the blue squares:
https://i.sstatic.net/V8YZs.jpg
The background XX's are to show where the images should be opaque
(Edit, separating this part from post to avoid confusion after it was solved in comments): There was an error because the Label in my skin did not have an id=“LabelDisplay”. The button in the downloaded tutorial project did not need this. Once I added the id=“LabelDisplay” this part was solved.
In the IconButton skin was an array constant exclusions. Simply adding the id of the BitmapImage to this array caused the BitmapImage to be excluded from colorization by SparkSkin class:
static private const exclusions:Array = ["labelDisplay","icon"];
It displays correctly now.