User manual
Tool Bar : Tools and Toolpickers
Page 126
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Lock and Group Toolpicker
Lock Selection [Ctrl + K] Locks Selected Clip(s)
Unlock Selection [Ctrl+Shift+K] Unlocks Selected Clip(s)
Group Selection [Ctrl + G] Groups Selected Clips
Ungroup Selection [Ctrl + U] Ungroup Selected Clips
Ungroup All [Ctrl+Alt+U] Ungroup all Groups in Composition