Docking slows down when dragging

[Igor.Antohin]

I have a quickly updated interface with a lot of UI elements. When trying to drag and drop RadPane, users encounter difficulties, on a slow computer it can take 30 seconds or more. I recorded a small video to make it clear what it was about. In my opinion, when dragging, it is necessary to disable the redrawing of elements inside the container, but how to do this?
I've tried set DragDropMode = DockingDragDropMode.Deferred, it's very fast, but when moving the cursor outside the main window, the application crashes.
Can you advise anything?

https://youtu.be/yD69Nj1B_Bc

[Kalin]

Hi Igor,

With the default DragDropMode whenever pane is dragged, its content is being removed from the current visual tree and placed inside a Window, so this operation with a lot of UI might cause delay.

As for the Deferred mode issue - we are not aware of it. Can you please provide sample project that reproduces it, so we can check it on our side? 

Basically if you provide sample project - we will investigate both of the cases and improve the control. Using the Deferred DragDropMode seems to be best solution here, so we would be glad to resolve the issue and allow you to use the feature.

I'm looking forward to hearing from you.

Regards,
Kalin
Progress Telerik

[Igor.Antohin]

Hello. It's too hard. But, I get your first example "Auto Generated Tag" from SDK samples browser -> Docking.
Next, I change  DragDropMode. If "Immediate" - a new window appears outside the main form. If "Deferred", then no.
Video: https://youtu.be/2sRHNw3Ec8s
PS. Even with empty windows in this example, dragging the window in "Immediate" mode is VERY slow. (CPU - I7-3820, 16Gb)

[Martin Ivanov]

Hello Igor,

I've tested both drag and drop modes in the AutoGeneratedTag SDK example, but I couldn't reproduce the performance issue in the Immediate DragDropMode. You can see the attached video. Also, you can check the attached project and let me know if I am missing anything. 

Additionally, you can check if the issue appears with the latest version of Telerik UI for WPF.

About the Deferred DragDropMode, in this case the drag/drop action of docked panes is allowed only inside of the RadDocking control. This is why when you drag out a pane. nothing happens. With this mode, you can undock a pane only via its context menu. 

Regards,
Martin Ivanov
Progress Telerik