I use one combobox to select a db, then the second shows documents in the selected db.
When I select a db, I want to generate the select list with documents in the selected db. I first considered running ViewRefreshFields, but WQO-agents don't get triggered by this.
It seems that running agents with the ToolsRunMacro @Command keeps the form as it was before the running of the agent.
The workaround, then, is quite simple. Add a hidden button (style="display:none") on the form. OnClick on the button, run the agent generating HTML (and ViewRefreshFields, if you need to refresh the form). Onchange in the db-combobox, click the button.
If you've used a similar approach, and found weaknesses with it, please let me know in a comment.