Icon Opacity "removes" Icon

[stormblade83]

Issue description

Hello there,
when I use the Icon Maker in the app and add an icon to the preview the icon is visible on the folder preview. But as soons as I touch the opacity slider it becomes completely invisible (even if I move the slider back to 100).
Any ideas on what I do wrong or is that a bug?

How to reproduce this issue?

Issue tracker rule checks (please read carefully)

• I have checked that my problem is not already reported
• I have checked that my problem is not already fixed

[stormblade83]

Additional finding: If I use an png or svg image the opacity slider simply does nothing at all (but at least the image doesn't disappear).