windowsforms-5687-controls-and-libraries-tree-list-feature-center-context-menus-control-the-availability-of-the-standard-context-menus-to-end-users.md
There are two ways to control the availability of the standard context menus to end-users: via corresponding options and by handling an event.
Menu options that control the availability of the standard context menus can be accessed via the TreeList.OptionsMenu property. These options allow you to disable or enable the column header and footer menus. Note that the Tree List elements for which menus are activated must be visible to allow the menus to be invoked. The visibility of these elements is controlled by the view options that can be accessed via the TreeList.OptionsView property.
The table below lists the types of menu and their visibility conditions.
| Menu Type | Visibility Condition |
|---|---|
| Column Header Panel Menu | The TreeListOptionsMenu.EnableColumnMenu property must be set to true. The TreeListOptionsView.ShowColumns property must be set to true to display column headers. |
| Row Footer Menu | The TreeListOptionsMenu.EnableFooterMenu property must be set to true. The TreeListOptionsView.ShowRowFooterSummary property must be set to true to display row footers. |
| Summary Footer Menu | The TreeListOptionsMenu.EnableFooterMenu property must be set to true. The TreeListOptionsView.ShowSummaryFooter property must be set to true to display the summary footer. |
| Node Menu | The TreeListOptionsMenu.EnableNodeMenu property must be set to true. |
For instance, you can write the following code to enable the column header menu and disable the footer menus.
treeList1.OptionsMenu.EnableColumnMenu = true;
treeList1.OptionsMenu.EnableFooterMenu = false;
TreeList1.OptionsMenu.EnableColumnMenu = True
TreeList1.OptionsMenu.EnableFooterMenu = False
The TreeList.PopupMenuShowing event fires each time an end-user attempts to invoke any standard context menu. The event’s parameters allow you to identify the type of menu, customize the menu or prevent it from being invoked. The following sample code handles the TreeList.PopupMenuShowing event to prohibit the menu for the Department column from being invoked.
void TreeList1_PopupMenuShowing(object sender, PopupMenuShowingEventArgs e) {
if (e.MenuType == TreeListMenuType.Column && e.HitInfo.Column.FieldName == nameof(SalesData.Department))
e.Allow = false;
}
Private Sub TreeList1_PopupMenuShowing(ByVal sender As Object, ByVal e As PopupMenuShowingEventArgs)
If e.MenuType = TreeListMenuType.Column AndAlso e.HitInfo.Column.FieldName = NameOf(SalesData.Department) Then e.Allow = False
End Sub