Theme color not applying to "hidden options" flyout

[fuzyll]

Version and Platform (required):

• Binary Ninja Version: 5.1.7997-dev
• Edition: any
• OS: macOS
• OS Version: 15.5
• CPU Architecture: aarch64

Bug Description:
Not sure when this became an issue, but certainly since the 4.0 theme redesign, we have a really bad color choice for the little double-chevron button that lets you access hidden options due to your viewport being too small:

They appear to be a darker gray color on both our default theme and on a light theme we ship with. I suspect it's not being themed, which either means we screwed something up or we've found a Qt bug as our themes do also set the default Qt colors to be used, too.

Steps To Reproduce:

1. Open a sidebar widget like Firmware Ninja's Board Description tab that have a bunch of horizontal controls
2. Make the widget small enough to hide some of them
3. Observe the little button that is, for all intents and purposes, completely invisible because of the color being used on it

Expected Behavior:
This should clearly and obviously be a clickable control as there are some very important options available behind it.