Variables are greyed for the Story out when using the API openPromptDialog()

[stephlef]

Dear experts,

I have story based on two live BW Queries.

When using the API Widget.getDataSource().openPromptDialog(); on a text field.onClick, on execution, the variable prompt opens up, but  the user cannot change any variable for the story, as Variables are greyed out, like this:

He may only change variables for a chart. I want the user to open prompt, be able to change variables for the story with this click on a text field, and not change variables using the menu { } icon.

Is there any way to achieve this? Maybe some options? I tried a few things there, to no avail, but I may have missed something.

Thanks for your help!

Stéphane