Expand/collapse groups in treeview by clicking the text

Question

How do I do so that it is possible to expand/collaps groups in the TreeView simply by clicking on the text, instead of clicking the arrow to the left.

Answer 1

You should create style for your Tree Item with next setter:

        <Style x:Key="TreeItemStyle"
               TargetType="{x:Type TreeViewItem}">                
            <Setter Property="IsExpanded"
                    Value="{Binding Path=IsExpanded, Mode=TwoWay}"/>
        </Style>

Then add to you group view data class observable property named IsExpanded:

    private bool _isExpanded;

    public bool IsExpanded
    {
        get
        {
            return this._isExpanded;
        }
        set
        {
            if (this._isExpanded != value)
            {
                this._isExpanded = value;
                this.OnPropertyChanged("IsExpanded");
            }
        }
    }

Then intercept hyper link click event and set IsExpanded as true:

    private void Hyperlink_Click(object sender, RoutedEventArgs e)
    {
        var dc = ((Hyperlink)sender).DataContext;
        if (dc is GroupViewData)
        {
            ((GroupViewData)dc).IsExpanded = true;
        }
    }

Of course, the best way is to use commands instead of click handlers, but I don't know composition of your presentation model so can't provide proper solution. I just must say that in our projects with alike requirements we successfully avoid any view code behind. God bless WPF!