Strange ComboBox drop list behavior

Ribbon for WPF Forum

Posted 13 years ago by wpf.acp
Version: 9.1.0507
Platform: .NET 3.5
Environment: Windows Vista (32-bit)
I have discovered a rather annoying but probably quite a minor bug. I have emailed the sample project to support email.

The context is very specific. Consider a window with a ribbon. A ribbon contains a ComboBox with some items. Nothing fancy here yet and all works nice. Now consider a wizard is launched in a separate modal window as a response to some event. The wizard has just a few pages and one of them has RadioButtonList. After closing the window with the wizard about 2 out of 3 times one tries to show Combo's drop list and merely move a mouse down towards list entries, the Combo decides to simply close (without a mouse click). The item beneath the mouse cursor becomes a new selected item in the Combo. Strange!

I took me a while to strip down my application to bare bones needed to reproduce the issue. I have tried putting RadioButtonList on the main window and the bug did not occur. I tried getting rid of the wizard and just using RadioButtonList in a second window. Even then nothing strange happened.

To successfully reproduce the issue one must have a Combo in a ribbon on a main window and a RadioButtonList in one of the wizard's pages. I could not reproduce it in any other way. Unfortunately for me, the exact context that causes the bug is used in my own app.

I have been fooled before into thinking there was a bug in one of your controls only to be embarrassed by the fact that WPF's own controls displayed the same "buggy" behavior. This time I have compared your Combo to WPF's own and the latter shows no glitch in the same context.

Comments (1)

Posted 13 years ago by Actipro Software Support - Cleveland, OH, USA
Thanks for the sample, it appears some code to handle access keys in the RadioButtonList was updating the ComboBox items in this scenario. We added a check for the next build that ensures the items modified belong to a RadioButtonList. That fixes this.

Actipro Software Support

The latest build of this product (v22.1.3) was released 29 days ago, which was after the last post in this thread.

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