When non-empty describes the text to use in a label of the GUI tab pages line. When empty and when the result is empty Vim will use a default label. See setting-guitablabel for more info.

The format of this option is like that of 'statusline'. 'guitabtooltip' is used for the tooltip, see below. The expression will be evaluated in the sandbox when set from a modeline, see sandbox-option. This option cannot be set in a modeline when 'modelineexpr' is off.

Only used when the GUI tab pages line is displayed. 'e' must be present in 'guioptions'. For the non-GUI tab pages line 'tabline' is used.

(default empty)

only available when compiled with GUI enabled