[Feature Request] Add TabSelected function #80

Panels has a SetChangedFunc, expose this for TabbedPanels such that when the user has selected a Tab, a function will be executed.

Use Case:

Let's say I have a TabbedPanel that consists of a Flex containing a List and TreeView. When .SetCurrentTab(name) is called, it will call a function to update the associated List.

Thanks for suggesting this.

Can you provide clarification as to why the the following behavior is observed:

b.lists is defined as an initialized cview.TabbedPanels
b.states is map of *cview.Lists with the associated tab string name

func (b *Browser) initializeTabbedList() {
	
    b.lists.SetChangedFunc(b.populate)
}

{...}

func (b *Browser) populate() {
	go func() {
    	listStr := b.lists.GetCurrentTab()
        {...}
        b.debugBar.SetText(listStr)
    }()
}

Works as expected. However, should I do the following:

func (b *Browser) populate() {
	listStr := b.lists.GetCurrentTab()
    go func() {
    	{...}
        b.debugBar.SetText(listStr)
    }()
}

will make the application unresposive.