Справка Collabora Office 24.04
Vertically aligns the top edges of the selected objects. If only one object is selected in Draw or Impress, the top edge of the object is aligned to the upper page margin.
Объекты выравниваются по верхнему краю самого верхнего объекта среди выбранных. To align the individual objects in a group,
to enter the group, select the objects, right-click, and then choose an alignment option.