Checkbox on Server Page marks DB occurrence always as modified after webget

Uniface: A checkbox on a Static Server Page (USP) marks DB occurrence always as
modified after webget.

Symptoms:
A checkbox on a Static Server Page (USP) marks DB occurrence always as modified
after webget.

To reproduce:

• USP with a DB entity painted.
• The USP is a maintenance page; it has
• one button to retrieve all occurrences and
• one button to store the update (if applicable)

• Modelled fields:

• PK string C40 text (key)
• FLD1 string VW10 text
• FLD2 boolean B checkbox
• FLD3 datetime E text
• FLD4 string VW100 text

• The write trigger of the entity has:
  ;- update timestamp on every insert and update
  FLD3=$datim

The retrieve works well.
However on every store the timestamp field is ALWAYS updated. This is when
checkbox is checked or unchecked.

When the Boolean checkbox fields (FLD2) is changed to a radio button (with
options F and T) or text the store ONLY updates the occurrences for which a
field is changed.

Another way is to change FLD2 to a hidden field in the layout and at JavaScript
to insert a visible checkbox which synchronizes with the hidden field.