Select

This toolbar has the same commands as the Selection menu. It is used to manipulate the selection in the subtitles list. The commands (accessible also via the right-click menu) are:

Select all - select all subtitles
Select none - deselect all subtitles
Invert selection - selected subtitles become unselected, unselected become selected
Select all marked - select all subtitles that are marked
Select all non-marked - select all subtitles that are not marked
Select next marked - search for a marked subtitle after the current subtitle and select it
Select previous marked - search for a marked subtitle before the current subtitle and select it

The selection can also be manipulated with the mouse and modifier keys like in other Windows applications:

Click - Select single item
Shift + Click - Select a range of items from the already selected one to the item you clicked on
Ctrl + Click - Toggle selection in single item, don't modify the selection in other items (i.e. add a single item to selection that is not required to be adjacent to an already selected item)