Having Sublime Text already running.
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In ST3 if I run subl FILEit opens a new tab in current Sublime Text window.
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In ST4 if I run sublime_text FILEit always open a new Sublime Text process (a separate ST icon in the macOS Dock to be clear). I’ve tried all command line options, no one changes this behavior.
I open like 40 files via command line every day. I hope this is a regression and not new expected behavior.