bafe0478_ROX_Filer_User_Manual__Key_or_mouse_button
[Action] Select a group of items by dragging a box around them. With the left mouse button, only the files in the box will be selected. If you hold down Control then the boxed items are added to the selection. If you use the middle button then the boxed items switch between being selected and unselected. [Key or mouse button] 
Drag (not over an item)
ROX-Filer User Manual
Key or mouse button