I have a DockContentHost which contains a split pane which contains a tab pane which contains a content pane. Inside this content pane I just have a combobox connected to an observable string collection.
1. When the content pane is loaded up normally the combobox works as expected. If i drag the pane out of the ContentHost and use the DocManager_ToolWindowLoaded event to set e.Window.UseOSNonClientArea = false, the combobox no longer 'drops down'.
2. When the content pane is loaded up normally the combobox works as expected. If i drag the pane out of the ContentHost WITHOUT setting e.Window.UseOSNonClientArea = false, the combobox works as intended. What am I missing?
When you set the UseOSNonClientArea to true, the AllowsTransparency of the WIndow that hosts the WPF window is set to true. I believe there is a bug in the OS or a driver relating to layered windows whereby the z-order of layered windows may be incorrect so the dropdown is actually going behind the floating window.