also found reported upstream in: https://github.com/transmission/transmission/issues/403
It seems to happen only when "libayatana-appindicator for Ubuntu-like tray" is enabled. I've modified the control file to: Build-Conflicts: libayatana-appindicator3-dev instead of Build-Depends: libayatana-appindicator3-dev and rebuilt package, and now it restores behaviour "left-click tray icon to show/hide transmission main window" which was working in previous Debian releases. Right-clicking the tray icon still shows window with: "Show Transmission / Open / Open URL / Pause etc" menu, as expected. So I guess that enabling ayatana-appindicator support breaks left-click action and make it same as right-click action. -- Opinions above are GNU-copylefted.
