Volume media key OSD's bar is barely visible on MATE with compositing enabled

[mz1193]

When compositing is active on MATE, the volume media key OSD's bar is a very light grey compared to the background's slightly darker grey. It's a minor usability issue, but I figured I should report it anyway.

[EMH-Mark-I]

Can you upload a screenshot of what you're seeing?

[mz1193]

This is what the OSD looks like when the volume is changed while compositing is active. As you can see, the indication of volume level is just barely visible. The issue isn't present when compositing is turned off, because MATE uses a simplified OSD in that case.