Getting a User Control to display in Toolbox pane

http://stackoverflow.com/questions/3829328/getting-a-user-control-to-display-in-toolbox-pane

answer:

You should right-click the Toolbox area, click on "Choose Items", in the ".Net Framwork Components" tab click on "Browse". Then select the .dll where your user control is and click OK. Then make sure the line of your newly added control is marked and click OK. It should be available now in the Toolbox.

Alternatively you could add the project of your user control in the solution and it should automatically be added to the toolbox (at the top).

more:
You still need to add the reference of the DLL.