Romain F. T. rrroschan@gmail.com Understand and change the app preferences. Preferences

The preferences dialog is splitted into 3 parts.

Image

You can choose the size and color of the default canvas used when creating a new file.

When a file is saved to the JPEG or the BMP file format, the transparency can't be kept. The application can replace the transparent pixels with something else: it can be white, black, or a checkboard of greys.

The option "default color" corresponds to the initial color of the canvas, which is usually the "default color" setting available in the previous section.

If the replacement you want depends on the image, it's also possible to open a dialog every time you save an image to one of these file formats: the choices available in that dialog will also be white, black, or a checkboard of greys.

You can also set how you want to zoom on the image: explanations about this setting can be found in this page about zooming.

Tools Appearance

You can set whether you prefer normal icons (16 pixels) or large icons (24 pixels).

Choosing if you want to display the names of the tools next to their icons is possible here, but the primary menu of the window already provides this option. You can also press F9.

 Additional tools

Among the available tools, a few are optional. You can uncheck the tools you don't need, or check the tools you need: the changes will be applied in the next window you open.

If a tool isn't activated by default, it's because it might be less reliable or useful than the enabled ones.

For example, the Paint bucket (which paints an area of contiguous pixels of the same color into a new color), and the Color selection (which creates a selection from an area of same color), rely on code whose behavior is sometimes unexpected: it might follow the edges of the area but paint the wrong side of them, and at worst it can even get stuck if the edges are too hard to follow, thus crashing before being able to paint!

On the other hand, the Brush works fine, but it has performance issues: if you press "undo" after having used the brush a few times, it'll freeze for a second. If you enable this tool, it's advised to save your image regularly to avoid problems.

The Color picker tool, which picks a color from the pixel you click, is disabled because it's a little redundant with the color picker from the color edition menu. The one from the color edition menu can pick an RGB color from any pixel of the display, while the tool is limited to pixels from the image but the colors it picks have a transparency channel (RGBA).

The Highlighter is a little redundant too, since you can do the same with the pencil and the adequate color application mode.

The tool named "Points" works fine but it's designed for a pretty specific captioning purpose that may not be useful to everyone.

See this page about tools for more information.
Window

Here you can set the size of the thumbnail preview, but using a bigger preview is not recommended for technical reasons.

You can also set the color of the background "behind" the canvas.

The "theme variant" option can force the app to use the dark variant of your current GTK theme.

Finally, it's possible to choose the layout of the user interface: the "Compact" layout, designed for the GNOME desktop, is well tested. Other options include the "elementary OS" layout, designed for the elementary OS desktop, and the traditional layout, for MATE or Cinnamon desktop.

In this context,"symbolic icons" means that the icons are monochrome (black if you use a light theme, or white if you use a dark theme). Otherwise they can be colorful (depending on your theme).