chart2: add some doxygen comments from Marco's talk

See
<https://conference.libreoffice.org/2019/program/schedule/sept-12th-thursday/>.

Change-Id: I914cfd02934206ab20a5e7af43ec5698dd9d29dc
Reviewed-on: https://gerrit.libreoffice.org/78829
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins

chart2/source/controller/inc/ChartWindow.hxx

@@ -63,6 +63,7 @@ public:
     virtual void Invalidate( InvalidateFlags nFlags = InvalidateFlags::NONE ) override;
     virtual void Invalidate( const tools::Rectangle& rRect, InvalidateFlags nFlags = InvalidateFlags::NONE ) override;
     virtual void Invalidate( const vcl::Region& rRegion, InvalidateFlags nFlags = InvalidateFlags::NONE ) override;
+    /// Notify the LOK client about an invalidated area.
     virtual void LogicInvalidate( const tools::Rectangle* pRectangle ) override;
 
     virtual css::uno::Reference< css::accessibility::XAccessible > CreateAccessible() override;

include/sfx2/lokcharthelper.hxx

@@ -20,6 +20,7 @@ namespace com::sun::star::frame { class XDispatch; }
 class SfxViewShell;
 class VirtualDevice;
 
+/// A class for chart editing support via LibreOfficeKit.
 class SFX2_DLLPUBLIC LokChartHelper
 {
 private:

sw/source/uibase/uno/unotxdoc.cxx

@@ -3503,7 +3503,7 @@ void SwXTextDocument::postMouseEvent(int nType, int nX, int nY, int nCount, int
     SwViewOption aOption(*(pWrtViewShell->GetViewOptions()));
     double fScale = aOption.GetZoom() / (TWIPS_PER_PIXEL * 100.0);
 
-    // check if user hit a chart which is being edited by him
+    // check if the user hit a chart which is being edited by this view
     SfxViewShell* pViewShell = pDocShell->GetView();
     LokChartHelper aChartHelper(pViewShell);
     if (aChartHelper.postMouseEvent(nType, nX, nY,