Several elements of the graph function as background panels for the other elements. These panels can be configured to display a visible background consisting of a solid color, a pattern, a gradient, or an image. Alternatively, the panel can be made transparent to show the underlying panel, if any. Where there are only transparent panels, the worksheet itself will be visible behind the graph.
The background panel Fill refers to the area which is behind the entire component. The Outline refers to a solid box which will be drawn around the edge of the component.
The Outline can be configured by selecting a color using the color picker widget and by choosing a size using the spin button box. A size of '-1' indicates that no line will be drawn, whereas sizes zero and above indicate the size of the line that will be drawn.
The Fill can be configured to be a pattern, which includes a solid color, a gradient or an image.
The fill using a pattern enables the panel background to consist either of a solid color, or of a solid color overlain by a pattern. The top drop down button, labeled Pattern, allows the user to select the pattern overlay from a number of different standard patterns. The pattern in the top left corner is an empty pattern which allows the background color indicated in the third drop down button to fill the panel. The middle drop down button, labeled Foreground, allows the user to select the color of the overlay in the pattern. The bottom drop down button, labeled Background, allows the user to select the color of the underlay. If the pattern is empty, the color of the Background will be the color of the entire panel.
If all of these buttons appear black, change the color of the Background to white to see the pattern and foreground color.
The background panel can be filled with a gradient transitioning either between two colors or between a color and a tone, either white or black. The top drop down button, labeled Direction, gives the user a number of choices for the direction in which the gradient will operate. The drop down button named Type allows the user to pick between gradients which transition between two colors, the 2 Colors option, and gradients that transition from a color to pure white or pure black, the Brightness option. The drop down buttons for the Start and End colors allow the user to pick the colors in the gradient. For the brightness gradients, a slider allows the user to select the transition direction. Moving the slider toward Brighter will fade the color to white whereas moving the slider toward Darker will fade the color toward black.
If all of these buttons appear black, change the color of the Start button to white to see the gradient.
The image background fill type allows the user to select an image to fill the background of the panel. The image can be in any file format supported by the gdk-pixbuf library as explained in Section 9.2 ― Images. The image can be fit in one of two ways. The image fit can be stretched so the image fills the whole panel area or the image fit can be wallpapered where the image is repeated in a tile pattern to fill up the whole background. The button labeled Select allows the user to call the file selector and choose the file which contains the desired image. On the GNOME desktop, the file chooser has a preview area to see the image before adding it. The size of the image, in pixels, is displayed in the configuration dialog as '# x #' where the number symbol indicates the number of pixels, and the number of pixels in each row comes before the number in each column.