In ST2 is more default shortcuts that helpfull working with this tool. But Sometimes there i'm installed many great plugins that are encountered shortcut conflicts with default keymap shortcuts. This problem was posted in ST2 forum: http://www.sublimetext.com/forum/viewtopic.php?f=4&t=5569&p=32246&hilit=keymap#p32246. So, maybe keymap manager is good resolution but I thing that better is situation when ST2 encounter shortcut conflicts (there is in Visual Studio or Jetbrains IDE tools as RubyMine) . So, another resolution is added bool option when an user would be decided that any plugin can't encounter default shortcut (users keymaping wolud be ignored).
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