GInk is an open-source application which allows drawing and annotating your screen, then saving the results. It's a handy way to highlight elements of a screenshot for presentations or demonstrations, or maybe to attach a quick note to a particular area of the screen.

Getting started is easy. There's no installation required, you can run the program, tap the system tray icon and draw on the screen immediately.

A toolbar at the bottom of the screen enables choosing alternative pens and colours. This looks basic - there's no interface to set colours or line widths - but there's more here than you'd expect. Drawing works with touch screens and has pen pressure support, and you can tweak colours by editing an INI file.

Made a mistake? GInk has you covered. There's an Undo tool to remove the last step, an Erase button wipes a specific element, or tapping Clear wipes the entire canvas so you can start again.

Screen annotation tools generally work by displaying a transparent form over the screen, blocking access to the windows underneath. This can be a problem, but gInk makes it easier to handle by offering a click-through mode. Turn this on, the annotations remain, but you can click on buttons or links on the screen and they'll work as usual.

When you're finished, tap the Snapshot icon and you're able to save a freehand rectangular area of the screen as an image.

There's no option to save the full screen or choose a file name, and the output folder must be set via an INI file. But this keeps it quick and easy to use, and overall it works very well.