I have myself done two comprehensive SRS (System Requirement Specification) documents – about 50 pages in length and full of UI diagrams – using OpenOffice Draw. The connectors, the basic shapes and  numerous the export options (or file formats) are all indispensable. But what was missing was a clipart of common shapes and elements.

I myself made tini-mini ODG files (OpenOffice Draw files) for combo boxes, dialog boxes and scrollbars, and re-used them in my diagrams.

Then, discovered this link to Custom OO shapes. Downloaded the .odg fies from this page and opened them in OpenOffice Draw Following is the screenshot of basic UI (user interface) elements like windows, dropdowns, frames, buttons, checkboxes etc.

Custom OO Shapes - GUI Elements and Controls

The way you can use them is:

1. Open the downloaded .odg files in OpenOffice Draw
2. Select the shape/component/element
3. Copy and paste the shape in your own diagram
4. Edit the shape – for example, change the label of the button from “OK” to “DONE”

Do not expect:

1. A Visio like, always accessible, sidebar/menu links to the clipart.
2. Colorful shapes