<p>As you've already pointed out, it's easier to simply call CComboBox::SetDroppedWidth(..) if all you want to do is make the droplist box wider than the combobox's editbox. HOWEVER, the droplist will always grow to the right-- not an ideal situation if your combobox is drawn on the right edge of a dialog.
<p>I wanted to have the droplist portion of the combo box line up with the editbox's right edge, so that the droplist grows to the left. By modifying your code, I was able to do this.
<font color="#009900">// TODO: Return a different brush if the default is not desired</font>
<font color="#0000ff">return</font> hbr;