When you right click in the Header Pane and select an entry, the 
currently selected item is effected.  This is contrary to common Windows 
control behavior in which right clicking effects the item under the mouse.

Ideally right clicking on the item and selecting an item from the menu 
should not effect the current selection, however this may be more 
difficult to implement.  Having right click first select the item under 
the mouse, then pop up the menu would be acceptable to me until a more 
ideal solution can be devised.