File chooser in Design Studio

Do you mean like this?

Yes, just like that.  Is that a custom form?

It's a custom form, but just coincidental. You could implement same functionality with a standard form. In this example the client wanted to store image URLs in a custom table. =

How was it done?

The Design Studio customization provides a "browse" button on the form so that a user can select a file from the local file system (or enter a URL). To implement this, originally the "BrowseForURL_ActiveX" function was added, which activated the ActiveX Common Dialog object. However, this failed in testing, since it required both the installation/registration of comdlg32.ocx on the users system, as well as allowing ActiveX objects to be run in the browser--a security risk that just wasn't worth it. In addition, ActiveX objects don't run in non-IE browsers without special handlers, etc.

So, a new (trickier, albeit less elegant) "BrowseForURL_Script" function is used. This script opens a hidden popup (hidden in the sense that it's underneath the main Portal window), which contains script to open a file dialog and set the selected filename into the Portal URL text object (_f8). The primary challenge (and the reason for having to create the popup) is that Design Studio doesn't allow for adding standard HTML input forms/text boxes. So, that was achieved by putting an input text box into a hidden "div" in the pop-up window, and "clicking" that object when the popup is loaded...