The GTK+ 3 Reference Manual can be viewed locally on a Linux computer in a program called Devhelp. When developing GTK+ 3 applications a local copy of the documentation can be very helpful.
A previous article explained how to get online and offline help for GTK+ using a web browser. Devhelp is an alternative application to using a web browser to view help files.
With Devhelp it is not necessary to navigate to the folder that contains the off-line documentation, the documentation is accessed in the left pane of Devhelp as shown in the above image.
Part 8 of GTK 3 Programming with C and Glade Tutorial
Update October 2019: See the video for information on getting context sensitive help in Glade after installing Devhelp and the GTK reference manual.
The Devhelp application can be installed in a Linux terminal window with the following command:
sudo apt-get install devhelp
After installation Devhelp can be found on the main menu of a Linux Mint computer under Menu → Programming → Devhelp.
Install Offline GTK+ 3 Reference Manual
The GTK+ 3 reference manual will not appear in Devhelp until it is installed on the system. To install the GTK+ 3 reference manual enter the following in a terminal window:
sudo apt-get install libgtk-3-doc
Now the next time that you open Devhelp, the GTK+ 3 manual will appear along with the GDK 3 reference manual.
Install the Glade Manual
Enter the following in a terminal window to install the Glade reference manual. Hitting the F1 key in Glade opens up the Glade reference manual, assuming Devhelp and this Glade manual are installed.
sudo apt install libgladeui-doc
Install the GLib Manual
Install the GLib reference manual with the following.
sudo apt install libglib2.0-doc
Install the Pango Manual
Pango is a library for layout and rendering of text in GTK. Install the Pango reference manual with the following line of code.
sudo apt install libpango1.0-doc
Install the Cairo Manual
Cairo is a library for 2D graphics used with GTK. Install the Cairo reference manual with the following line of code.
sudo apt install libcairo2-doc
Install the GDK-PixBuf Reference Manual
Install the GDK-PixBuf reference manual with the following line of code.
sudo apt install libgdk-pixbuf2.0-doc
Finding the GTK+ 3 Reference Manual
Also see the article GTK+ 3 Help Finding GTK3 Documentation for more information on finding the GTK offline documentation in the file system and opening it in a browser instead of Devhelp.