1. Link to http://zssdemo.zkoss.org/zssdemo/excel_like then click File -> New.
2. Click on cell C3 and type formula "=SUM(A1,A2)", then press enter.
3. Click to cell C3 again, and focus on the formula bar.
4. Press key "Home", then press "Left arrow" key, the formula is messed.
You can repeat step 4 to see the messed up result.