Flood Select
For this tool, simply select edges around a region of a polygon mesh, then [shift] + select a face, vertex, or UV within that region and execute "Flood Select" to select all faces/vertices/UVs in the encompassed mesh region:
For this tool, simply select edges around a region of a polygon mesh, then [shift] + select a face, vertex, or UV within that region and execute "Flood Select" to select all faces/vertices/UVs in the encompassed mesh region: