It’s not mobile that is broken, it’s the desktop build. It’s incorrectly applying sRGB adjustments to the colors in the color picker. It’s very easy to confirm:
- Produce a solid color image in some image editor like MS Paint
- Import into UE4 and place it into UMG as an image widget
- Add an empty (white) image widget
- Try tinting the white image to match the imported image.
You just can’t. The color picker actually reads the correct color (as displayed in the Hex field), but it thinks the color is linear and tries to gamma-correct it. If you disable the sRGB preview flag, you’ll see the correct color, but UMG will use the wrong color instead.
Here’s a screenshot showing the problem:
I picked the red surrounding the heart to tint the white background. It picked the [correct color][2], but displays it with incorrect gamma.
Disabling the sRGB preview displays the correct color in the picker window, but it doesn’t make UMG use it correctly.