py dock id

Possible values of dock id (string constants):

• DOCK_NONE: panel is not docked.
• DOCK_LEFT: 1st left dock.
• DOCK_LEFT1: 2nd left dock (not used for panels).
• DOCK_RIGHT: 1st right dock.
• DOCK_RIGHT1: 2nd right dock (not used for panels).
• DOCK_BOTTOM: 1st bottom dock.
• DOCK_BOTTOM1: 2nd bottom dock (not used for panels).
• DOCK_TOP: top dock (not used for panels).