Some (mostly HIG) tweaks to chart elements panel

As I wanted to represent subsections as frames (it looks kinda
better with bold labels), I tried to emulate grid behaviour by
putting widgets into 2 size groups

Other tweaks include disabling legend position listbox when legend
is not to be shown and missing clear() of that listbox

Change-Id: I0b635fe5aba1580542cf982e2e6be02eb0056352
Reviewed-on: https://gerrit.libreoffice.org/17386Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Katarina Behrens <Katarina.Behrens@cib.de>

chart2/source/controller/sidebar/ChartElementsPanel.cxx

@@ -310,6 +310,7 @@ ChartElementsPanel::ChartElementsPanel(
     get(mpCBGridHorizontalMinor,  "checkbutton_gridline_horizontal_minor");
 
     get(mpLBLegendPosition, "comboboxtext_legend");
+    get(mpBoxLegend, "box_legend");
 
     Initialize();
 }
@@ -342,6 +343,9 @@ void ChartElementsPanel::dispose()
     mpCBGridVerticalMinor.clear();
     mpCBGridHorizontalMinor.clear();
 
+    mpLBLegendPosition.clear();
+    mpBoxLegend.clear();
+
     PanelLayout::dispose();
 }
 
@@ -491,7 +495,10 @@ IMPL_LINK(ChartElementsPanel, CheckBoxHdl, CheckBox*, pCheckBox)
     else if (pCheckBox == mpCB2ndYAxisTitle.get())
         setTitleVisible(mxModel, TitleHelper::SECONDARY_Y_AXIS_TITLE, bChecked);
     else if (pCheckBox == mpCBLegend.get())
+    {
+        mpBoxLegend->Enable( bChecked );
         setLegendVisible(mxModel, bChecked);
+    }
     else if (pCheckBox == mpCBGridVerticalMajor.get())
         setGridVisible(mxModel, GridType::VERT_MAJOR, bChecked);
     else if (pCheckBox == mpCBGridHorizontalMajor.get())

chart2/source/controller/sidebar/ChartElementsPanel.hxx

@@ -23,6 +23,7 @@
 #include <sfx2/sidebar/IContextChangeReceiver.hxx>
 #include <sfx2/sidebar/SidebarModelUpdate.hxx>
 #include <svx/sidebar/PanelLayout.hxx>
+#include <vcl/layout.hxx>
 #include "ChartSidebarModifyListener.hxx"
 
 #include <com/sun/star/util/XModifyListener.hpp>
@@ -95,6 +96,7 @@ private:
     VclPtr<CheckBox> mpCBGridHorizontalMinor;
 
     VclPtr<ListBox> mpLBLegendPosition;
+    VclPtr<VclHBox> mpBoxLegend;
 
     css::uno::Reference<css::frame::XFrame> mxFrame;
     ::sfx2::sidebar::EnumContext            maContext;