One annoyance I found with ShowDialog() vs ShowDialog(this).
Run the TestApp, show the newform.ShowDialog(), click “show Desktop” on your taskbar or Quick launch toolbar, click on the TestApp on the taskbar. It shows the Mainform. You have to do an Alt-Tab to get to your newform.
VS
Run the TestApp, show the newform.ShowDialog(this), click “show Desktop” on your taskbar or Quick launch toolbar, click on the TestApp on the taskbar. It shows the newform on top.