Sublime command to choose a syntax definition from a quick panel.
Via Package Control.
Press CtrlShiftY to show the syntax selector panel (CommandShiftY on Mac OS).
To open the Syntax Selector settings, run Preferences: Syntax Selector from the command palette or choose Preferences → Package Settings → Syntax Selector → Preferences: Syntax Selector from the menubar.
show_hidden_syntaxes: boolean (default: false)
If true, show all syntax definitions. If false, do not show hidden syntax definitions.
If true, then when you highlight a syntax definition in the syntax selector panel, that definition will be temporarily applied to your code. If you cancel the panel, the original syntax definition will be restored.