The TopMost style doesn't work with MDI child form. However, you may handle the Leave event of your top most MDI child, and set the focus back to it. When you want to switch the Top Most MDI child, you may remove the handler and add it to another form. Here is a sample code:private void MDI_Leave(object sender, System.EventArgs e)
{
Form mdi = (Form)sender;
if(mdi != null)
mdi.Focus();
}//Set the event handle
TopForm.Leave += new EventHandler(this.MDI_Leave);
{
Form mdi = (Form)sender;
if(mdi != null)
mdi.Focus();
}//Set the event handle
TopForm.Leave += new EventHandler(this.MDI_Leave);
则不会被挡住,why???