A coupler to form a frame which then holds a pane to an opening in a door or the like, the coupler comprising: a first and a second frame member (10A, 10B); a first coupling member operatively connected to the first frame member; a second coupling member operatively connected to the second frame member; and a connector having opposite first and second parts for connecting with the first and second coupling members respectively, the first part having a first fastener for bodily engagement with the first coupling member and the second part having a second fastener for bodily engagement with the second coupling member; such that the first and second frame members (10A, 10B) are coupled together by the coupler, with the connector extending through said opening and connecting with the first and second coupling members (101, 102), on opposite sides of said door or the like to thereby hold said pane in said opening, characterized in that, the first fastener and the first coupling member include corresponding inter-engageable formations for bodily inter-engagement to prevent separation between the first fastener and the first coupling member, wherein the first fastener is configured to initially connect with the first coupling member through relative linear movement in a direction transverse to the connector, and the second fastener and the second coupling member include inter-engageable formations for bodily engagement to prevent separation between the second fastener and the second coupling member, wherein the second coupling member is configured to subsequently connect with the second fastener through a linear movement of the second coupling member relative to the second fastener in a direction parallel to the connector. a first and a second frame member (10A, 10B); a first coupling member operatively connected to the first frame member; a second coupling member operatively connected to the second frame member; and a connector having opposite first and second parts for connecting with the first and second coupling members respectively, the first part having a first fastener for bodily engagement with the first coupling member and the second part having a second fastener for bodily engagement with the second coupling member; such that the first and second frame members (10A, 10B) are coupled together by the coupler, with the connector extending through said opening and connecting with the first and second coupling members (101, 102), on opposite sides of said door or the like to thereby hold said pane in said opening, characterized in that, the first fastener and the first coupling member include corresponding inter-engageable formations for bodily inter-engagement to prevent separation between the first fastener and the first coupling member, wherein the first fastener is configured to initially connect with the first coupling member through relative linear movement in a direction transverse to the connector, and the second fastener and the second coupling member include inter-engageable formations for bodily engagement to prevent separation between the second fastener and the second coupling member, wherein the second coupling member is configured to subsequently connect with the second fastener through a linear movement of the second coupling member relative to the second fastener in a direction parallel to the connector.