Designer's "Edit Palette" window does not retrieve saved alpha value

1) Select any widget and click "palette" in Property Edit window.
2) In "Edit Palette" window, click any color role to open the "Select Color" dialog box
3) In "Select Color" window, change the Alpha channel to a value other than 255 and click Ok to close dialog box
4) Re-open "Select Color" dialog box, the alpha channel value is always 255. But the actual alpha value is changed in saved *.ui file.