Thanks for your quick reply.
I tried the suggested way but its not helping.
Let me explain the required scenario again.
On diagram's NODE click(mouse left button click), I want to show MiniToolBar(third-party control) on it.
To show mini tool bar, it requires
1) UIElement placementTarget
2) Point clientLocation
in placementTarget I am giving diagram instance and to Point "e.MousePosition.X,e.MousePosition.Y".
It works fine in 100% zoom factor but as zoom factor change it is not visible as its (location-co-ordinates)position getting changed.
I also tried following lines of code
Point newPoint = diagram.DocumentPlane.PointFromScreen(new Point(e.MousePosition.X, e.MousePosition.Y));
Point newPoint = diagram.DocumentPlane.PointFromScreen(Mouse.GetPosition(sender as Diagram));
Please let know what should I give the UIElement and Point, so that for any zoom value toolbar will be visible in diagram above the node.
Thanks in advance.
Harshal