Sprites 32 and 156 function inconsistently, and usually incorrectly. When an Osprey arrives at a gate (var E6 values 01-03), it is supposed to raise its nacelles to the vertical position. Under most circumstances, this does not happen. However, checking the vehicle details window reveals that it thinks the nacelles are in the vertical position. Furthermore, if the vehicle details window is open when the Osprey arrives at the gate, the rotors will rise to their correct (nacelles-vertical) position, but the nacelles don't follow.
These pseudo-sprites work correctly for entering the hangar (var E6 value 00)
Further checking shows that the Osprey is not the only aircraft with this problem. The attached test_p.grf is supposed to create planes that display the current value of the variable passed as a parameter. If you set the parameter to 230 (0xE6), the exact same bug is observed: although the vehicle details window is aware that the value has changed, the main view is not.
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