docs-desktop/dotnet-desktop-guide/framework/winforms/controls/merging-menu-items-in-the-windows-forms-menustrip-control.md

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Merging Menu Items in MenuStrip Control	03/30/2017	MenuStrip [Windows Forms], merging merging [Windows Forms], general concepts	95e113ba-f362-4dda-8a76-6d95ddc45cee

Merging Menu Items in the Windows Forms MenuStrip Control

If you have a multiple-document interface (MDI) application, you can merge menu items or whole menus from the child form into the menus of the parent form.

This topic describes the basic concepts associated with merging menu items in an MDI application.

General Concepts

Merging procedures involve both a target and a source control:

• The target is the xref:System.Windows.Forms.MenuStrip control on the main or MDI parent form into which you are merging menu items.

• The source is the xref:System.Windows.Forms.MenuStrip control on the MDI child form that contains the menu items you want to merge into the target menu.

The xref:System.Windows.Forms.MenuStrip.MdiWindowListItem%2A property identifies the menu item whose drop-down list you will populate with the titles of the current MDI parent form's MDI children. For example, you typically list MDI children that are currently open on the Window menu.

The xref:System.Windows.Forms.ToolStripMenuItem.IsMdiWindowListEntry%2A property identifies which menu items come from a xref:System.Windows.Forms.MenuStrip on an MDI child form.

You can merge menu items manually or automatically. The menu items merge in the same way for both methods, but the merge is activated differently, as discussed in the "Manual Merging" and "Automatic Merging" sections later in this topic. In both manual and automatic merging, each merge action affects the next merge action.

xref:System.Windows.Forms.MenuStrip merging moves menu items from one xref:System.Windows.Forms.ToolStrip to another rather than cloning them, as was the case with xref:System.Windows.Forms.MainMenu.

MergeAction Values

You set the merge action on menu items in the source xref:System.Windows.Forms.MenuStrip using the xref:System.Windows.Forms.MergeAction property.

The following table describes the meaning and typical use of the available merge actions.

MergeAction Value	Description	Typical Use
xref:System.Windows.Forms.MergeAction.Append	(Default) Adds the source item to the end of the target item's collection.	Adding menu items to the end of the menu when some part of the program is activated.
xref:System.Windows.Forms.MergeAction.Insert	Adds the source item to the target item's collection, in the location specified by the xref:System.Windows.Forms.ToolStripItem.MergeIndex%2A property set on the source item.	Adding menu items to the middle or the beginning of the menu when some part of the program is activated. If the value of xref:System.Windows.Forms.ToolStripItem.MergeIndex%2A is the same for both menu items, they are added in reverse order. Set xref:System.Windows.Forms.ToolStripItem.MergeIndex%2A appropriately to preserve the original order.
xref:System.Windows.Forms.MergeAction.Replace	Finds a text match, or uses the xref:System.Windows.Forms.ToolStripItem.MergeIndex%2A value if no text match is found, and then replaces the matching target menu item with the source menu item.	Replacing a target menu item with a source menu item of the same name that does something different.
xref:System.Windows.Forms.MergeAction.MatchOnly	Finds a text match, or uses the xref:System.Windows.Forms.ToolStripItem.MergeIndex%2A value if no text match is found, and then adds all the drop-down items from the source to the target.	Building a menu structure that inserts or adds menu items into a submenu, or removes menu items from a submenu. For example, you can add a menu item from an MDI child to a main xref:System.Windows.Forms.MenuStripSave As menu. xref:System.Windows.Forms.MergeAction.MatchOnly allows you to navigate through the menu structure without taking any action. It provides a way to evaluate the subsequent items.
xref:System.Windows.Forms.MergeAction.Remove	Finds a text match, or uses the xref:System.Windows.Forms.ToolStripItem.MergeIndex%2A value if no text match is found, and then removes the item from the target.	Removing a menu item from the target xref:System.Windows.Forms.MenuStrip.

Manual Merging

Only xref:System.Windows.Forms.MenuStrip controls participate in automatic merging. To combine the items of other controls, such as xref:System.Windows.Forms.ToolStrip and xref:System.Windows.Forms.StatusStrip controls, you must merge them manually, by calling the xref:System.Windows.Forms.ToolStripManager.Merge%2A and xref:System.Windows.Forms.ToolStripManager.RevertMerge%2A methods in your code as required.

Automatic Merging

You can use automatic merging for MDI applications by activating the source form. To use a xref:System.Windows.Forms.MenuStrip in an MDI application, set the xref:System.Windows.Forms.Form.MainMenuStrip%2A property to the target xref:System.Windows.Forms.MenuStrip so that merging actions performed on the source xref:System.Windows.Forms.MenuStrip are reflected in the target xref:System.Windows.Forms.MenuStrip.

You can trigger automatic merging by activating the xref:System.Windows.Forms.MenuStrip on the MDI source. Upon activation, the source xref:System.Windows.Forms.MenuStrip is merged into the MDI target. When a new form becomes active, the merge is reverted on the last form and triggered on the new form. You can control this behavior by setting the xref:System.Windows.Forms.ToolStripItem.MergeAction%2A property as needed on each xref:System.Windows.Forms.ToolStripItem, and by setting the xref:System.Windows.Forms.ToolStrip.AllowMerge%2A property on each xref:System.Windows.Forms.MenuStrip.

See also

• xref:System.Windows.Forms.ToolStripManager
• xref:System.Windows.Forms.MenuStrip
• MenuStrip Control
• How to: Create an MDI Window List with MenuStrip
• How to: Set Up Automatic Menu Merging for MDI Applications