UDAV have main window divided by 2 parts in general case and optional bottom panel(s). Left side contain tabs for MGL script and data arrays. Right side contain tabs with graphics itself, with list of variables and with help on MGL. Bottom side may contain the panel with MGL messages and warnings, and the panel with calculator.
Main window is shown on the figure above. You can see the script (at left) with current line highlighted by light-yellow, and result of its execution at right. Each panel have its own set of toolbuttons.
Editor toolbuttons allow: open and save script from/to file; undo and redo changes; cut, copy and paste selection; find/replace text; show dialogs for command arguments and for plot setup; show calculator at bottom.
Graphics toolbuttons allow: enable/disable additional transparency and lighting; show grid of absolute coordinates; enable mouse rotation; restore image view; refresh graphics (execute the script); stop calculation; copy graphics into clipboard; add primitives (line, curve, box, rhombus, ellipse, mark, text) to the image; change view angles manually. Vertical toolbuttons allow: shift and zoom in/out of image as whole; show next and previous frame of animation, or start animation (if one present).
Graphics panel support plot editing by mouse.
Short command description and list of its arguments are shown at the status-bar, when you move cursor to the new line of code. You can press F1 to see more detailed help on special panel.
Also you can look the current list of variables, its dimensions and its size in the memory (right side of above figure). Toolbuttons allow: create new variable, edit variable, delete variable, preview variable plot and its properties, refresh list of variables. Pressing on any column will sort table according its contents. Double click on a variable will open panel with data cells of the variable, where you can view/edit each cell independently or apply a set of transformations.
Finally, pressing F2 or F4 you can show/hide windows with messages/warnings and with calculator. Double click on a warning in message window will jump to corresponding line in editor. Calculator allow you type expression by keyboard as well as by toolbuttons. It know about all current variables, so you can use them in formulas.