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How to detect if dropdown of combobox opens above or underneath?

Posted By:      Posted Date: October 25, 2010    Points: 0   Category :WPF

I've got a custom UserControl embedded in a DataGrid. This control consists of a grid with two rows; the first, containing a title (of what the content of the dropdown in the combo box represents) and the second containing the combo box itself.

My problem is, that when the combo box is located somewhere in the lower part of the screen, the popup shows up above the combo box and hides the title. I'd like to detect this and swap rows to show the title underneath the combo box.

What I've tried so far:
I've hoped to be able to get the upper left corner of the (opened) popup and check it against the location of the UserControl itself with following code


    private void cbItems_DropDownOpened(object sender, EventArgs e)
      var popup = (Popup)cbItems.Template.FindName("PART_Popup", cbItems);
      var p = popup.PointToScreen(new Point(0, 0));
      var p2 = this.PointToScreen(new Point(0, 0));

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