Hi Eric,
Thank you for your interest in Syncfusion Products.
It is possible using ToolStripControlHost class. Please refer the below code snippets that illustrates this:
[C#]
UserControl1 UCtrl2 = new UserControl1();
ToolStripControlHost host1 = new ToolStripControlHost(UCtrl2);
this.toolStripEx2.Items.Add(host1);
Please find the simple sample in the following link:
http://websamples.syncfusion.com/samples/Tools.Windows/F76420/main.htmIn this sample Usercontrol2 occupy the exact size of toolStripExContainer.
Please let me know if any concerns.
regards,
Hema