InRibbonGallery changes into DropDownButton after DropDown is opened and closed

[pschimmel]

I found another layouting issue in the InRibbonGallery. I don't know if it is related to the other issues, I reported earlier, so I will just open another issue.

The problem appeared in our real application, where it looked much worse, but it took a while until I could make a sample project where the issue is reproducible.

Here's a video of the issue:
GalleryCollapsesToDropDown.zip

As you can see, I reduced the size of the main window until one of the galleries reduces. Then I just open and close the DropDown. My expectation is that the gallery remains in the same state, but actually it reduces to a DropDownButton.

You can use the project to reproduce the issue:
FluentTest.zip

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Environment

• Fluent.Ribbon v8.0.0
• Windows 10
• .NET Framework 4.7.2