If only the mouse was being used for selection, then it needs to reset itself to the state before dropping down
if arrow keys had been used then it needs to keep that selection
The combobox chaches the current selection, so when arrow keys are used it has the correct selection
when the mouse is used it holds the old selection. So therefore, we can compare against it
to determine what to do.
Bug 63247
r=waqar sr=hyatt
Re-wrote nsComboboxFrame.
removed the obsolete nsHTMLAtoms: comboText,comoTextSelected,comTextSelectedFocus,dropDownVisible,
dropdownHidden, dropDownBtnOut, dropDownBtnPressed,
Added nsHTMLAtoms::combobox, nsLayoutAtoms::popupList
Renamed dropDownList to dropDownListPseudo
Added "arrow.gif" as to be used the background-image for the combobox button
ua.css - added rules for select to differentiate between comboboxes and listboxes.
Added style rules to more closely match the XPTOOLKIT XPWidgets look.
removed the following :-moz-combobox-text, -moz-combobox-textselected
nsIFormControlFrame.h - Added SetSuggestedSize method.
nsButtonControlFrame - Implemented SetSuggestedSize.
nsCSSFrameConstructor.cpp - Rewrote ConstructSelectFrame.
nsIWidget.h -Added GetAbsoluteBounds method.
nsWindow.cpp - Implemented GetAbsoluteBounds.
