Really fix spurious asserts in wxGTK wxDataViewCtrl::EditItem()

This replaces the changes of 24c0401
which, for some reason, used a global variable for storing whether the
selection function had been already set or not, when this clearly is a
per-control (or per-selection, but this seems one and the same) bit of
information.

Replace global ms_firstTime with a wxDataViewCtrlInternal field to avoid
asserts as soon as EditItem() is called on more than one wxDataViewCtrl.

See #17946.

(cherry picked from commit 81d9952)

src/gtk/dataview.cpp

@@ -163,16 +163,16 @@ gboolean wxdataview_selection_func(GtkTreeSelection * WXUNUSED(selection),
 class wxGtkTreeSelectionLock
 {
 public:
-    wxGtkTreeSelectionLock(GtkTreeSelection *selection)
+    wxGtkTreeSelectionLock(GtkTreeSelection *selection, bool& alreadySet)
         : m_selection(selection)
     {
         wxASSERT_MSG( !ms_instance, "this class is not reentrant currently" );
 
         ms_instance = this;
 
-        if ( ms_firstTime )
+        if ( !alreadySet )
         {
-            ms_firstTime = false;
+            alreadySet = true;
             CheckCurrentSelectionFunc(NULL);
         }
         else
@@ -225,15 +225,13 @@ class wxGtkTreeSelectionLock
     }
 
     static wxGtkTreeSelectionLock *ms_instance;
-    static bool ms_firstTime;
 
     GtkTreeSelection * const m_selection;
 
     wxDECLARE_NO_COPY_CLASS(wxGtkTreeSelectionLock);
 };
 
 wxGtkTreeSelectionLock *wxGtkTreeSelectionLock::ms_instance = NULL;
-bool wxGtkTreeSelectionLock::ms_firstTime = true;
 
 //-----------------------------------------------------------------------------
 // wxDataViewCtrlInternal
@@ -344,6 +342,11 @@ class wxDataViewCtrlInternal
     wxGtkDataViewModelNotifier *m_notifier;
 
     bool                  m_dirty;
+
+public:
+    // Allow direct access to this one from wxDataViewCtrl as it's just a
+    // simple flag and it doesn't make much sense to encapsulate it.
+    bool                  m_selectionFuncSet;
 };
 
 
@@ -3419,6 +3422,7 @@ wxDataViewCtrlInternal::wxDataViewCtrlInternal( wxDataViewCtrl *owner, wxDataVie
     m_dropDataObject = NULL;
 
     m_dirty = false;
+    m_selectionFuncSet = false;
 
     m_gtk_model = wxgtk_tree_model_new();
     m_gtk_model->internal = this;
@@ -4849,7 +4853,8 @@ void wxDataViewCtrl::DoSetCurrentItem(const wxDataViewItem& item)
     // Unfortunately the only way to do it seems to use our own selection
     // function and forbid any selection changes during set cursor call.
     wxGtkTreeSelectionLock
-        lock(gtk_tree_view_get_selection(GTK_TREE_VIEW(m_treeview)));
+        lock(gtk_tree_view_get_selection(GTK_TREE_VIEW(m_treeview)),
+             m_internal->m_selectionFuncSet);
 
     // Do move the cursor now.
     GtkTreeIter iter;
@@ -4890,7 +4895,8 @@ void wxDataViewCtrl::EditItem(const wxDataViewItem& item, const wxDataViewColumn
     // Unfortunately the only way to do it seems to use our own selection
     // function and forbid any selection changes during set cursor call.
     wxGtkTreeSelectionLock
-        lock(gtk_tree_view_get_selection(GTK_TREE_VIEW(m_treeview)));
+        lock(gtk_tree_view_get_selection(GTK_TREE_VIEW(m_treeview)),
+             m_internal->m_selectionFuncSet);
 
     // Do move the cursor now.
     GtkTreeIter iter;