add optional helpid to add_button

Change-Id: I9606d0788c78397feb0840463991c5498e759b5a
Reviewed-on: https://gerrit.libreoffice.org/51703Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

include/vcl/weld.hxx

@@ -135,7 +135,8 @@ private:
 public:
     virtual int run() = 0;
     virtual void response(int response) = 0;
-    virtual void add_button(const OUString& rText, int response) = 0;
+    virtual void add_button(const OUString& rText, int response, const OString& rHelpId = OString())
+        = 0;
     virtual void set_default_response(int response) = 0;
 };
 

vcl/source/app/salvtables.cxx

@@ -468,11 +468,12 @@ public:
         m_xDialog->EndDialog(nResponse);
     }
 
-    virtual void add_button(const OUString& rText, int nResponse) override
+    virtual void add_button(const OUString& rText, int nResponse, const OString& rHelpId) override
     {
         VclButtonBox* pBox = m_xDialog->get_action_area();
         VclPtr<PushButton> xButton(VclPtr<PushButton>::Create(pBox, WB_CLIPCHILDREN|WB_CENTER|WB_VCENTER));
         xButton->SetText(rText);
+        xButton->SetHelpId(rHelpId);
         xButton->Show();
         m_xDialog->add_button(xButton, nResponse, true);
     }

vcl/unx/gtk3/gtk3gtkinst.cxx

@@ -1635,9 +1635,11 @@ public:
         gtk_dialog_response(m_pDialog, VclToGtk(nResponse));
     }
 
-    virtual void add_button(const OUString& rText, int nResponse) override
+    virtual void add_button(const OUString& rText, int nResponse, const OString& rHelpId) override
     {
-        gtk_dialog_add_button(m_pDialog, MapToGtkAccelerator(rText).getStr(), VclToGtk(nResponse));
+        GtkWidget* pWidget = gtk_dialog_add_button(m_pDialog, MapToGtkAccelerator(rText).getStr(), VclToGtk(nResponse));
+        if (!rHelpId.isEmpty())
+            ::set_help_id(pWidget, rHelpId);
     }
 
     virtual void set_default_response(int nResponse) override