Select the mass brush tool from the context menu.
Now draw a line to cross some faces.
You can select
all crossed faces (even if they are parts of some surfaces) only
or
all crossed faces and surfaces (where every connected surface of any crossed face will be selected).
This is usefull to paint wide spread areas along a given line.
All faces remains elected.
Those selected faces can now be smoothed, converted to a surface or coloured with a brush from the toolbar or from the context (selection).
Besides that selected faces can be modified with keybord keys, if you select the selector here.
