skins2: fix #689 (text control refresh issue)

This patch redefines the method associated with visibility
to ensure that the latest text is displayed when
the text control gets visible

modules/gui/skins2/controls/ctrl_text.cpp

@@ -211,6 +211,23 @@ void CtrlText::onUpdate( Subject<VarText> &rVariable, void* arg )
 }
 
 
+void CtrlText::onUpdate( Subject<VarBool> &rVariable, void *arg  )
+{
+    // Visibility changed
+    if( &rVariable == m_pVisible )
+    {
+        if( isVisible() )
+        {
+            displayText( m_rVariable.get() );
+        }
+        else
+        {
+            notifyLayout();
+        }
+    }
+}
+
+
 void CtrlText::displayText( const UString &rText )
 {
     // Create the images ('normal' and 'double') from the text

modules/gui/skins2/controls/ctrl_text.hpp

@@ -124,6 +124,9 @@ private:
     /// Method called when the observed variable is modified
     virtual void onUpdate( Subject<VarText> &rVariable, void* );
 
+    /// Method called when visibility is updated
+    virtual void onUpdate( Subject<VarBool> &rVariable , void* );
+
     /// Display the text on the control
     void displayText( const UString &rText );