workaround is to override the OnInitialized of the custom column: protected override void OnInitialized(EventArgs e) {/* //if XAML assemblies Theme theme = StyleManager.GetTheme(this); Type themeType = null; if (theme != null) { themeType = theme.GetType(); } this.DefaultStyleKey = new ThemeResourceKey() { ElementType = typeof(Telerik.Windows.Controls.GridViewColumn), ThemeType = themeType };*/ }
The bug can also occur on Custom Controls not derived of any telerik class. But it is also fixed by this workaround.