This is not completely fixed.  To reproduce:

Right-click on Start button.
Click Add.
Double-click in Arguments field, type "abc", hit Return.
Double-click in Arguments, click on "..." button.
Change text to "def" and click OK.  Arguments fields correctly shows "def".
Click on "..." button again.  Displayed text reverts to "abc" in Arguments field
   which seems like a bug.
Change "def" in popup window to "ghi" and click OK.
   A second Edit Text window appears with contents "ghi" (huh?).
   Click OK in second window.  Now text is changed to "ghi" in Arguments field.