The RadWindow's size shrinks while dragging it on a monitor with high DPI scale which causes it to shake a bit. In other words, the dragging is not smooth.
This was reproduced on a monitor with DPI scale set to 175%.
This is reproducible if you set the RadWindowInteropHelper.AllowTransparency on the RadWindow control (regardless of the value - True or False).
This is more noticeable in .NetCore projects.
Environment: VS Community 2019 (16.0.3), with .NET Framework 4.8 (release version, run-time and developer pack installed), Windows 10 Pro October 2018
Telerik UI version: latest (2019.1.220.45)
When VS2019 opened, Telerik UI for WPF should have been found under the "Extension" menu --> Telerik --> Telerik UI for WPF. However, there is only "Telerik UI for WinForms" under "Telerik" now. There is neither "Telerik scenario" in the "Add New Item" window so no RadForms can be created. Manually replacing <Window> in XAML to <telerik:RadWindow> does change the appearance of the window in the designer, but the properties in the Property window does not change accordingly to RadForms but still WPF standard Form ones. Toolboxes shows current lists of Telerik UI for WPF controls and they can be correctly created (at least RadButton). "Repair" in the Progress Control Panel doesn't fix this problem.
The issue is reproducible when the DPI is changed at runtime(new feature introduced with Windows 10) and therefore the application is not notified for the change. In order the application to be aware of the change the user have to logout and sign in (or the application should be DPI aware).
In WPF browser application it is possible to move the focus of a focused TextBox control inside the RadWindow to the parent page with Shift+Tab keyboard combination