Hi Ubaid,
We can make the dock enabled control visible again after closing it by using the following code.
//To make visible the control after closing it
if (!this.dockingManager1.GetDockVisibility(ctrl))
this.dockingManager1.SetDockVisibility(ctrl, true);
I have attached a sample that illustrates the same. Please have a look at it and let me know if this helps you.
http://websamples.syncfusion.com/samples/Tools.Windows/f61827/Main.htmBest regards,
Golda