Fix resetting text override when manually entering the text

The entered text wasn't taken into account, as the override was still
used when its numeric value was retrieved by GtkSpinButton using our
"input" handler, so reset the override now as soon as we get "changed"
signal.

src/gtk/spinctrl.cpp

@@ -176,14 +176,22 @@ void wxSpinCtrlGTKBase::GTKSetTextOverride(const wxString& text)
     m_textOverride->m_text = text;
 }
 
-void wxSpinCtrlGTKBase::GTKResetTextOverride()
+bool wxSpinCtrlGTKBase::GTKResetTextOverrideOnly()
 {
     if ( !m_textOverride )
-        return;
+        return false;
 
     delete m_textOverride;
     m_textOverride = NULL;
 
+    return true;
+}
+
+void wxSpinCtrlGTKBase::GTKResetTextOverride()
+{
+    if ( !GTKResetTextOverrideOnly() )
+        return;
+
     // Update the text part to reflect the numeric value now that we don't
     // override it any longer, otherwise we'd keep showing the old one because
     // the text is updated by GTK before "value" is generated.
@@ -524,7 +532,10 @@ bool wxSpinCtrlGTKBase::GTKOutput(wxString* text) const
 
 void wxSpinCtrlGTKBase::GTKTextChanged()
 {
-    GTKResetTextOverride();
+    // We can't use GTKResetTextOverride() itself here because it would also
+    // reset the value and we do not want this to happen -- the value is being
+    // changed to correspond to the new text.
+    GTKResetTextOverrideOnly();
 
     wxCommandEvent event( wxEVT_TEXT, GetId() );
     event.SetEventObject( this );