Install libgtkextra-3.0 by entering the following commands in the terminal:
sudo apt update sudo apt install libgtkextra-3.0
Description:
useful set of widgets for creating GUI's for GTK+
The library includes the following widgets: . GtkSheet, a matrix widget; GtkPlot, which allows you to draw high quality scientific plots; the package also includes GtkPlot3D and GtkPlotPolar; GtkPlotCanvas is a GtkFixed subclass and allows you to DnD plots etc. The distribution includes also a PostScript driver. GtkIconList, which allows you to display a table of xpm icons; GtkDirTree, which allows you to navigate the file-system; GtkFileList which displays the contents of a given directory using fancy icons for different types of files; GtkIconFileSelection, a file selection dialog using icons; GtkItemEntry, a GtkEntry subclass; GtkFontCombo, providing two combos to select among the 35 standard Adobe PostScript fonts; GtkComboBox, which allows you can pack whatever you want, from a calendar to a clist; GtkColorCombo, to pickup the color you like the most, within a palette; GtkBorderCombo, a fancy GtkComboBox subclass; GtkCheckItem, a GtkCheckButton hack with the look and feel of the Redmond95 theme.
Homepage: http://gtkextra.sourceforge.net/cms/
Version: 3.3.4-1
Section: universe/devel