# Owl's Blog on .NET development

Component Owl codes Better ListView control all night so you don't have to.

## Custom Behavior of Group Headers in Better ListView

Blog Post by Libor Tinka published on Friday, 20 January 2012 in Better ListView

When developing our desktop applications, me and Jiri needed to adjust behavior of group headers in the Better ListView control.

We discovered that making group header behavior customizable would be useful not only for us, but for other developers who utilize Better ListView as well, so we implemented this feature officially in Better ListView 2.5.0.

There are two new properties: ShowDefaultGroupHeader and GroupHeaderBehavior.

# Hiding the Default Group Header

The ShowDefaultGroupHeader is initially set to true. This means that the default group (the group containing items which do not have a specific group) have its header displayed:

Default group header is visible

When ShowDefaultGroupHeader is set to false, the “Default” group header on top can be hidden:

Default group header is hidden

# Adjusting Group Header Behavior

The group headers have two kinds of behavior. They can be focused and can cause selection of items. Both of these functions can be invoked by keyboard and mouse.

The GroupHeaderBehavior property allows changing this behavior for keyboard and mouse separately.

By default, the property is set to BetterListViewGroupHeaderBehavior.All, so that all functions of the group header are turned on.

You may want to make group headers completely non-interactive. This can be done by setting the property to BetterListViewGroupHeaderBehavior.None.

Other values of the enum can be combined to create desired behavior.

Keyboard:

- Focus only
- Focus and select items in the group

Mouse:

- Focus
- Select items in the group
- Highligh when mouse cursor is over the group header

The expand button of group headers can still be used even if the group header has all the behaviors turned off. If you need to hide the expand button as well, set BetterListViewGroup.AllowShowExpandButton to false.

# Use Case: Metadata Viewer

Here Better ListView is used for viewing image metadata tags:

Metadata View window

Only one tag can be selected at a time, so clicking on a group header has no effect on selection and need not to be highlighted.

One may still need, however, to allow focusing the group header with keyboard and mouse so that it is possible to collapse/expand the group with arrow keys. The desired behavior can be set this way:

C#

[csharp gutter=”false” toolbar=”false”]listView.GroupHeaderBehavior = (BetterListViewGroupHeaderBehavior.KeyboardFocus & BetterListViewGroupHeaderBehavior.MouseFocus);[/csharp]

Visual Basic

[vb gutter=”false” toolbar=”false”]listView.GroupHeaderBehavior = (BetterListViewGroupHeaderBehavior.KeyboardFocus And BetterListViewGroupHeaderBehavior.MouseFocus)[/vb]

Tags: behavior, better listview, custom, customize groups in listview, customize list view group headers, default, group, group header, header, hide, hot, list view group headers

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