While both the left and right mouse buttons do require a solid press, they're large and responsive all the way up to the apex of the mouse, and there's actually only a single spot (on the extreme upper-right-hand corner of the right mouse button) where it won't actuate if pressed down.
But they had to wait too long, much too long, for the infernal elevator, which liked to clamor below with buckling metal and other echoes of motion the minute the call button was pressed, but tended to dally there before zooming right past, up and up, to some grander view of Bequia Tower.