tdf#100864 Assign a tooltip to the button to close pane

which appears at the top-right corner of both Impress's
Slide Pane and Draw's Page Pane.

Change-Id: Ida52ccc35e42546cd6260001e22335b04608034d
Reviewed-on: https://gerrit.libreoffice.org/40803Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Takeshi Abe <tabe@fixedpoint.jp>

include/sfx2/strings.hrc

@@ -255,6 +255,7 @@
 #define STR_SIGNATURE_OK                        NC_("STR_SIGNATURE_OK", "This document is digitally signed and the signature is valid.")
 #define STR_SIGNATURE_SHOW                      NC_("STR_SIGNATURE_SHOW", "Show Signatures")
 
+#define STR_CLOSE_PANE                          NC_("STR_CLOSE_PANE", "Close Pane")
 #define STR_SFX_DOCK                            NC_("STR_SFX_DOCK", "Dock")
 #define STR_SFX_UNDOCK                          NC_("STR_SFX_UNDOCK", "Undock")
 

sfx2/source/dialog/titledockwin.cxx

@@ -217,6 +217,7 @@ namespace sfx2
         // Get the closer bitmap and set it as right most button.
         BitmapEx aBitmapEx(SFX_BMP_CLOSE_DOC);
         m_aToolbox->InsertItem(1, Image(aBitmapEx));
+        m_aToolbox->SetQuickHelpText(1, SfxResId(STR_CLOSE_PANE));
         m_aToolbox->ShowItem( 1 );
     }