Thank you for the provided pictures.
The observed behavior is actually the expected one. The reason for it is that the RadMultiColumnComboBox contains a RadWatermarkTextBox inside it, as well as the box of the selected item. In the first picture the textbox cannot fit next to the selected item on the right and that is why it is placed below it. On the 2nd picture, when the space is increased, there is enough space for the control on the right.
That said, in order to reduce the MinWidth of the RadWatermarkTextBox, you can set the EditorMinWidth
property to a smaller value.
Please, give this approach a try and let me know, if it is suitable for your scenario.
I am looking forward to your reply.
Progress TelerikWant to extend the target reach of your WPF applications, leveraging iOS, Android, and UWP? Try UI for Xamarin
a suite of polished and feature-rich components for the Xamarin
framework, which allow you to write beautiful native mobile apps using a
single shared C# codebase.