sd: Don't crash when the sidebar is hidden

Change-Id: I09a5019a98b529ba11f07392906a3e0fb7bc1bac
(cherry picked from commit c511b279)
Reviewed-on: https://gerrit.libreoffice.org/18243Reviewed-by: Jan Holesovsky <kendy@collabora.com>
Tested-by: Jan Holesovsky <kendy@collabora.com>

sd/source/ui/slidesorter/controller/SlsSlotManager.cxx

@@ -179,7 +179,8 @@ void SlotManager::FuTemporary (SfxRequest& rRequest)
 
         case SID_SLIDE_TRANSITIONS_PANEL:
         {
-            // Make the slide transition panel visible in the sidebar.
+            // First make sure that the sidebar is visible
+            pShell->GetViewFrame()->ShowChildWindow(SID_SIDEBAR);
             ::sfx2::sidebar::Sidebar::ShowPanel(
                 OUString("SlideTransitionPanel"),
                 pShell->GetViewFrame()->GetFrame().GetFrameInterface());

sd/source/ui/table/tablefunction.cxx

@@ -207,8 +207,8 @@ void DrawViewShell::FuTable(SfxRequest& rReq)
         }
         else
         {
-            // Make the table design panel visible (expand it) in the
-            // sidebar.
+            // First make sure that the sidebar is visible
+            GetViewFrame()->ShowChildWindow(SID_SIDEBAR);
             ::sfx2::sidebar::Sidebar::ShowPanel(
                 OUString("ImpressTableDesignPanel"),
                 GetViewFrame()->GetFrame().GetFrameInterface());

sd/source/ui/view/ViewShellImplementation.cxx

@@ -119,8 +119,8 @@ void ViewShell::Implementation::ProcessModifyPageSlot (
 
         if (!pArgs || pArgs->Count() == 1 || pArgs->Count() == 2 )
         {
-
-            // Make the layout menu visible in the tool pane.
+            // First make sure that the sidebar is visible
+            mrViewShell.GetViewFrame()->ShowChildWindow(SID_SIDEBAR);
             sfx2::sidebar::Sidebar::ShowPanel(
                 OUString("ImpressLayoutsPanel"),
                 mrViewShell.GetViewFrame()->GetFrame().GetFrameInterface());