prefer PIDE editor operations;
apply_query: insist in non-outdated snapshot via editor.current_command;
tuned signature;
Isabelle application bundle for MacOS
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Requirements:
* CocoaDialog 2.1.1 http://cocoadialog.sourceforge.net/
* Platypus 4.7 http://www.sveinbjorn.org/platypus
Preferences: Install command line tool
* final packaging:
hdiutil create -srcfolder DIR DMG