Left-click meant two things at once. Brief, it opened a part's data sheet; held down, it grabbed that part to move it. Two gestures on one button, and nothing to tell you which one was expected.
Several players left during the very first mission without ever finding how to push a solenoid's plunger. If that was you, it wasn't you.
From now on, a brief right-click on a part opens its sheet. A right-click on empty space closes it, and a cross has appeared in the sheet's corner. Left-click means one thing only: your hand.
Three welcome side effects. Switches and dials finally have a sheet you can read — they used to take the click for themselves. You can check a roller's speed on a running robot without shoving it by missing your aim. And nothing opens by accident any more.
If the game did not open in your language, the language menu is in the settings: English and French are both complete.