In addition to this, layers can be masked by clipping them to a lower layer. Work can be done on separate layers, which can be grouped and have opacity masks. There is also a set of vector drawing tools intended for inking, which, like the raster tools, can be configured to be pen pressure-sensitive. Various raster drawing tools are implemented, such as the Airbrush, Watercolor, Pen, and Marker, which can all be easily customized, and stored in slots in the user interface of the application. Colors can be stored in the swatches panel. An application-wide scratchpad (which can be used as a color mixing panel) is provided, which is saved between sessions. It is also possible to open multiple viewports to the same document. The toolbar on the top part of the screen also includes a button to mirror the drawing view without mirroring the actual drawing. The drawing canvas can be both zoomed and rotated using the sliders on the navigator or the hotkeys configured on the keyboard. The user interface allows multiple documents to be opened at the same time. SAI is a lightweight painting application. ( February 2023) ( Learn how and when to remove this template message) Unsourced material may be challenged and removed. Please help improve this section by adding citations to reliable sources.