Favor mouse Drag and Drop functionality instead of cumbersome arrow buttons used for item organization in dialog boxes. While already present in Fields tab in Layer Properties, still missing everywhere else. Partially requested in Draggind Legend Items, this idea suggest to remove this inconsistency in functionality throughout the ArcGIS, especially in:
Layer Properties, Symbology tab
Legend Properties, Legend Items tab
Label Priority Ranking
Group Layer properties, Group tab
Improve inner dialog box drag and drop functionality and extend it beyond single dialog box extent to provide better and flexible interconnection between workspace elements. For example: D&D layer from TOC to Legend, D&D layer to/from Layer Group dialog, D&D layer in Legend dialog Items tab from Map Layers to Legend Items etc.