Bug 1376489 - Allow stub installer header text to use the full window width. r=rstrong

MozReview-Commit-ID: L5OdDqdS12e

--HG--
extra : rebase_source : 0f0b6ee362c34bbd722a70517c7932d300e78a2b

browser/installer/windows/nsis/stub.nsi

@@ -819,7 +819,9 @@ Function createInstall
   ; Resize the Dialog to fill the entire window
   System::Call 'user32::MoveWindow(i$Dialog,i0,i0,i $8,i $9,i0)'
 
-  ${NSD_CreateLabelCenter} 25% ${NOW_INSTALLING_TOP_DU} 50% 47u "$(STUB_INSTALLING_LABEL)"
+  ; The header string may need more than half the width of the window, but it's
+  ; currently not close to needing multiple lines in any localization.
+  ${NSD_CreateLabelCenter} 0% ${NOW_INSTALLING_TOP_DU} 100% 47u "$(STUB_INSTALLING_LABEL)"
   Pop $0
   SendMessage $0 ${WM_SETFONT} $FontInstalling 0
   SetCtlColors $0 ${INSTALL_BLURB_TEXT_COLOR} transparent