Created attachment 25049 [details]
Screenshots for steps 1 and 4
1) Set custom background color for some widget (for example, button) in its properties dialog (see 1.png)
2) Save and close storyboard
3) Reopen storyboard and open properties dialog for same widget as in step 1.
4) RGB components of red color are shown instead of color set in step 1 (see 2.png)
Version of Visual Studio extension is 188.8.131.52, Visual Stduio version is 15.3.5 (last available).
This should already be fixed in newer builds. If it is not in the 15.4 builds which have been in the preview channel for the last few months then it will be in the 15.5 builds which will be in the preview channel shortly!