The MILCMD_VISUAL_SETCOLORTRANSFORMROOT packet instructs the composition engine to treat a specified visual as the root of the composition tree, or to stop treating a specified visual as the root.
The server MUST<5> emit this command packet for the root of a visual tree, with the fColorTransformRoot field set to true. If the server changes the shape of the tree via a MILCMD_TARGET_SETROOT packet such that a visual that was previously a root of a visual tree stops being a root, then the server MUST emit this command packet for that visual with the fColorTransformRoot field set to false.
The client MAY ignore this packet if any of the following conditions are true:
The client renders root and non-root visuals identically.
The client can determine the root of a visual tree by traversing the tree.
The client determines the root of the visual tree by processing the MILCMD_TARGET_SETROOT packet.
messageSize (4 bytes): A 32-bit unsigned integer. The size of this message in bytes. The value of this field MUST be set to 0x00000010.
controlCode (4 bytes): A 32-bit unsigned integer containing the control code for this message. The value of this field MUST be equal to 0x00000029.
targetResource (4 bytes): A 32-bit unsigned integer. The value of this field MUST be set to a valid resource handle referencing a resource of type TYPE_VISUAL or TYPE_WINDOWNODE. This handle identifies the resource that is the target for this message.
fColorTransformRoot (4 bytes): A 32-bit integer Boolean value. If true, the specified visual MUST be treated as the root of the composition tree.