UI Image Set editor
Open rs.iop in IOP Manager, then press Load to edit xml/uiimageset.xml. Textures are read from the packs next to it (map.iop, map2.iop, sakura.iop, …).
Drag a box to move it, its handles to resize · Alt/right-drag or drag empty space to pan · wheel to zoom · arrows nudge (Shift ×10) · Delete removes