Debugging: How to check for errors in your script

How to debug without a breakpoint

Watch tooltip while entering code: Suggestions appear as long as code is correct.
F1 or right mouse on any symbol shows its value or shows context sensitive help.
SingleStepMode (Alt+S or Enter key or toolbar) shows 8-digit results.
A SUBROUTINE or FUNCTION is only single stepped if SHIFT is hold down on entry.
Hide tested code in a subroutine to make it single step in step mode.
TraceMode (Alt+T or toolbar) traces statements automatically.
F1 or right mouse: select "Break on change" in popup.
Define a SUBROUTINE Fn (Fn = F2...F9). Then Fn can be called asynchronously (Toolbar or keyboard).
Alt+Q to quickly test a statement. Local variables can be used or changed.

How to debug with a trace or break line. Select or combine any of:

F1 or right mouse on whitespace: select RunTo a bookmarked line. BREAK.
- array ! displays array in a dialog. BREAK.
- string ! displays string in a dialog. BREAK.
- IF( val >= 3.7 ) WRITE(Messagebox) val ! conditional BREAK if true
- IF( KEY(SHift) ) WRITE(msg) "break because the shift key is pressed" ! User BREAK
- BEEP("c e g") ! TRACE: sounds a specific tune when this line is executed
- WRITE(WINdowhandle=wh) x, txt, matrix, etc ! TRACE: writes to window wh (if wanted in a loop). ( WINDOW(WIN=wh) must precede).
- DLG(Edit=array, WINdowhandle=whd) ! TRACE (WIN= causes noWait). Displays array updates
- WRITE(Message, Name) x ! BREAK. Insert this line to script. A message box opens and displays x = value
- WRITE(m="Y?",n) "any message", text, x, y ! BREAK. Displays ?, text=..., x=..., y=..., "Yes No Cancel"
- WRITE(m="yA", OnButton="PROC") "call PROC?" ! BREAK. "Yes No". If buttonA ("Yes") call PROC, else continue
- WRITE(StatusBar, Name) val ! TRACE: writes updated "val=..." to the statusbar
- WRITE(Row=1, Col=8, Name, BackColor=12, Point=32) x, y, z ! TRACE: writes updated to script window, large print on red
- SYSTEM(RUN=x) ! BREAK run mode for x = 0, else start RUN mode.
AXIS with rolling coordinates is useful to display longer running data series. TRACE.