Open source tool to draw GUI mockups

Question

I want to draw a sketch for a graphical user interface. Is there a slim open source software for Linux to draw user interfaces?

I used sometimes the combination of Qt designer and Inkscape or Gimp as workaround, but I prefer to have it in one tool and without the need of the very large Qt suite.

• open-source and free of charge
• runs on Linux
• draw GUI items (buttons, windows, textboxes, scrollbars)
• draw annotations (arrows, annotations, freestyle pen)
• objects in saved files should still be editable (no flat screenshot)

Answer 1

Draw.io can be used both online and offline (you can download for Linux), it's open source, can draw GUI items and annotations, and allows you to save the file locally or on the cloud to edit it later (file is saved in XML format).

Answer 2

Pencil is a tool I have used for UI mockups. And there’s quite a few tutorials for it on YouTube.