A door operator comprises a rotary shaft, a chain disk for rotating the rotary shaft, and a locking mechanism for locking the rotary shaft. The locking mechanism comprises a bidirectional rotary block, a plurality of push pins and anti-rotation posts. When the chain disk rotates, the push pins urge the bidirectional rotary block to rotate the rotary shaft, and when the rotary shaft rotates, the of anti-rotation posts lock the bidirectional rotary block, and preclude the rotary shaft from rotating.

A fenestration assembly includes a sash, a frame surrounding the sash, and at least one screen assembly mounted in at least one of: the top portion and the bottom portion. The frame includes a top portion, a bottom portion, and two jambs forming first slots extending lengthwise along at least a portion of the jamb. The first slots each include a screen edge retention feature. The screen assembly includes a roller assembly substantially hidden from view, a screen material attached to the roller assembly, and a plurality of raised features. Edges of the screen material extend into the first slots. The raised features are attached to each of the edges of the screen material. The raised features are configured to engage the screen edge retention features and retain each of the edges of the screen material at least partially within the first slot of each of the two jambs.

An actuating system for a window shade includes a transmission axle, a brake assembly and a clutch. The transmission axle is rotationally coupled to an axle adapter for rotation about a longitudinal axis. The brake assembly includes an arrester, a rotary element rotatable about the longitudinal axis, and a shift collar configured to couple and decouple the rotary element from the arrester, the shift collar switching from a decoupling position to a coupling position in response to a rotation of the rotary element in a first direction and from the coupling position to the decoupling position in response to a rotation of the rotary element in an opposite second direction. The clutch can couple and decouple the axle adapter from the rotary element, and has a clutch actuator rotatable about the longitudinal axis to switch the clutch between a clutch coupling state and a clutch decoupling state.