I have a WinForm with many text boxes and several combo boxes.  I also
have a toolstrip with cut, copy, and paste icons.  When a user clicks
one of the buttons (cut/copy/paste), I want to get the current active
control and if it is a textbox or a combobox, to then copy the
selected text to the clipboard (or do the appropriate option based on
the button).  I can get all of this to work just fine with the
textboxes.  To figure out the active control, I am using the
GetFocus() pointer from "user32.dll".  This is the only way I could
find to do what I needed to do.  Below is an example of how my code
looks.
[DllImport("user32.dll")]
public static extern IntPtr GetFocus();

private void btnCopy_Click(object sender, EventArgs e)
       {
           FocusControl = Control.FromHandle(GetFocus());

           if (FocusControl != null)
           {
               if (FocusControl.GetType().ToString() ==
"System.Windows.Forms.TextBox")
               {
                   TextBox myTextBox = (TextBox)FocusControl;
                   if (!string.IsNullOrEmpty(myTextBox.SelectedText))
                   {
                       Clipboard.SetText(myTextBox.SelectedText);
                   }
               }
               else if (FocusControl.GetType().ToString() ==
"System.Windows.Forms.ComboBox")
               {
                   ComboBox myComboBox = (ComboBox)FocusControl;
                   Clipboard.SetText(myComboBox.SelectedText);
               }
           }
       }

This works great for textboxes, but if the focus is on a combobox, the
FocusControl object is null, so it doesn't fall into the if
statement.  I've tried using the ActiveControl method, but couldn't
figure out how to drill down to the actual control that had focus.
All it gave me back was the control that the textbox was on, not the
actual textbox control.  I'm sure I could iterate through each child
control, but I figured there had to be an easier way.  Any help would
be greatly appreciated.