Found finally a workaround. Do force a ajax render="id of the dynamicResource" or simply @all whenever there might have happened an action to change the filename or mime type within the UI.

Note: In the Showcase this is done but only with event="valueChange" and this seems not to work there somehow. In my quite similar case it works with @all and no event selector

r52777: corrected ace:dynamicResource > Advanced demo to correctly update the entered file name

The ICE-10654 issue was indeed fixed. However, there were some issues with the demo itself.

First, the ace:textEntry component to change the file name had two ace:ajax tags. Simply having <ace:ajax render=@form" /> is enough to update the value in the server.

The other issue is that values in a form are not submitted and updated in the server when the ace:dynamicResource type is 'image'. This is simply, because an anchor element is rendered with the image and the URL, so the form is not submitted. In order for the form to be submitted when the ace:dynamicResource component is clicked, the type must be 'button'. So, if an image is to be rendered for this button, it will have to be done via CSS, as shown in the updated demo. The 'image' time should only be for static resources that are not expected to change dynamically.