between the flange 14 and the rib 30 viewed another way the set joint compound c forms a wedge of hardened material that is not readily pulled out from under the rib 30 nor from the joint compound that is set over the outward side of the rib as indicated at 38 as seen in fig3 and 3a the ribs 30 can be formed having a curved profile to create a larger void space 36 compared to straight angled ribs an alternate embodiment of the drywall element 110 having a compound locking feature 112 is illustrated in fig4 and 4a in this embodiment the ribs 130 are formed relatively straight from the base 132 to the end 134 of the rib 130 and with a bead 140 running longitudinally along the end 134 of the rib 130 the bead 140 appears as a rounded shape in cross section the bead 140 creates a larger interference element in the set compound c from which the rib 130 has to be pulled to dislodge the element 110 although both embodiments of the element 10 110 are shown with ribs 30 130 extending from both the inner 24 124 and outer 26 126 surfaces of the flange 14 114 it will be appreciated that the elements 10 110 could be formed with ribs 30 130 extending from one or the other surface as desired it is also to be understood that the ribs 30 130 on the outer surface 26 126 bond to compound c that is applied to the outer surface 26 126 or over the flange 14 114 in this configuration loosening of the compound c on the outer surface 26 126 will be lessened when the element 10 110 is struck conversely ribs.