Don't show panel on taskbar

I have done some widgets, there are mainwidget, and several dialogs that show as modal.
How I can hide panels in taskbar?I want that there is only one panel.
When I open some dialog, on the taskbar appear new panel..
Usually, I have opened 2 dialogs (both in modal mode), and on the taskbar is 3 same panels.

Set the parent on a dialog, that should hide any taskbar buttons for the seperate dialogs.

Thanks ! it is help me!