The ornamental design for a three panelcorner grouping for a gazebo, as shown and described.
FIG. 1 is a perspective view of a gazebo featuring four three-panel corner groupings in accordance with the invention;
FIG. 2 is a front elevation of the gazebo of FIG. 1 (the left side, right side, and rear elevations of the gazebo being identical to the front elevation as shown in FIG. 1);
FIG. 3 is a top plan view of the gazebo of FIG. 1; and,
FIG. 4 is a bottom plan view of the gazebo of FIG. 1.
Broken lines are used in the Drawings to denote certain subject matter, for example, environmental structure or boundaries, that are for illustrative purposes only and form no part of the claimed design.