I have a form with more than 20 fields to fill and this is in a popup dialog. What is the best way to handle this?
Seeing you are already using categories, and what I understand is you don't want to have scrolling inside your popup?
If your user does not need to see all the information filled into your form, depending on the process I see two options where the form fields are divided into smaller blocks (for example your categories?), tabs or wizard style process.
Many Windows applications use tabs to group settings into smaller blocks.
Example of form split into tabs: http://dhtmlx.com/docs/products/dhtmlxForm/samples/05_integration/05_split.html
What platform would this be in? For mobile devices? For desktops?
If it is just for desktops, a box with a scroll-able region should suffice. Or if there are so many fields, then it probably deserves its own page.
For mobile devices, I think it would be preferable to group the fields into logical categories and separate them into pages
For example, a user details form could have the following categories
- Mobile number
- Email Address
- Home Address