i was in correspondence with Martin Ivanov and we worked out some information i want to share.
Situation: Multi-Monitor-Environment with Taskbars on every monitor. Docking with floating panes and taskbar icon like: https://github.com/telerik/xaml-sdk/tree/master/Docking/FloatingPaneTaskbarIcons
Problem: when moving a ToolWindow to the next monitor the taskbar icon stays on the monitor it was created.
Reason: some native WPF window behavior
Workaround: Create a custom ToolWindow and "refresh" icon when window is moved to an other monitor:
I hope this helps. If someone optimize the code and find a solution to prevent the flickering on "refresh" please share it!