`ALTER PAGE … SET PageSize` fails with "pluggable property not found" on a DataGrid 2 that `CREATE` accepted the same property on

[MendixMau]

Summary

The create path and the alter path resolve pluggable-widget property names from different
tables.

create or modify page accepts PageSize: 20 on a datagrid widget and writes it — the grid
demonstrably paginates at 20 in the running app. ALTER PAGE rejects the same property name on
the same widget:

alter page Common.RunRegister { set PageSize = 10 on dgApprovalRuns };
→ Error: failed to set: failed to set PageSize on dgApprovalRuns:
  pluggable property "PageSize" not found

mxcli check --references passes the script clean. The failure appears only at exec.

Environment

• mxcli v0.20.0
• Mendix 11.13.0
• Linux container

Aggravating factors

1. mxcli is not transactional across statements. The failing set aborted the script, so a
   second, unrelated statement behind it (a dynamictext Content change on a different page)
   never applied. A one-line property tweak leaves a two-page script half-done.
2. DESCRIBE PAGE does not round-trip PageSize at all — the property is absent from the
   dump — so the current value cannot be read back out of the model to confirm what was set.

Impact

The workaround is to re-emit the entire page with create or modify page, changing only the one
value. On this project that turned a two-value edit into a 190-line script, and re-emitting a
page wholesale carries its own risk of drift against whatever else has touched it since.

Expected

ALTER PAGE … SET <prop> accepts every property create … (<prop>: …) accepts on the same
widget type. Failing that, check --references should reject the unknown property so the failure
is caught before the model is touched.

Related

MDL-WIDGET16 (DataGrid 2 stores no column names, so ALTER PAGE must address columns by derived
name). Same underlying cause: the DG2 pluggable-property surface exposed on create is not the
surface exposed on alter.

#414 covers the general case (SET reaching only DynamicText/Content and reporting property not found for other widget properties); this is the DataGrid 2 PageSize instance of it, where CREATE accepts the very property ALTER rejects.