How to display custom caption buttons in WinForms Docking Manager when the window is floating?
Show custom caption button
In DockingManager, you can add custom caption buttons to the caption bar in floating state using the ShowCustomButtonsInFloating property.
C#
this.dockingManager1.ShowCustomButtonsInFloating = true;
VB
Me.dockingManager1.ShowCustomButtonsInFloating = True
Sample: http://www.syncfusion.com/downloads/support/directtrac/general/CustomButtons1514324162.zip
UG document link: https://help.syncfusion.com/windowsforms/dockingmanager/floating-window#show-custom-buttons-in-float-window
