GTK1 Interface

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GTK logo.svg

This article applies to GTK+ Widgetsets only.

See also: Multiplatform Programming Guide


Warning: Gtk 1 development has been discontinued. The GTK2 Interface is now the default interface for *nix. Patches however are still accepted to fix compilation when Gtk1 breaks. There are no core Lazarus developers that still use the gtk1 interface. The information below may be outdated.


The gtk1 widgetset is quite stable. There are still some bugs and missing properties.

The documentation can be found here.

The minimum Gtk 1 version supported is Gtk 1.2.18

Other Interfaces

Platform specific Tips

Interface Development Articles

Using the Gtk1 interface under macOS

If you want to build gtk1 applications on macOS you need X11 and GTK 1.2 too:

Apple X11: On a new system: choose "Customize" in the install dialog, check "X11".

On an already installed system:

MacOSX 10.3: download at:

MacOSX 10.4: install X11 from the DVD.

GTK 1.2: Downloading the GTK packages and installing them properly can be a time consuming task. Therefore there are various package managers. One of them is fink:

Download fink from; follow the install instructions.

In the Terminal, run

       sudo /sw/bin/apt-get install gdk-pixbuf gtk+ gtk+-data gtk+-shlibs gtk-doc gtk-engines

The X11 application is in /Applications/Utilities/X11. You can drag and drop it on the dock so you can start it with one click. X11 on Leopard (10.5) is different and starting is not recommended.

Tip: Most X11 programs, including Lazarus, expect to receive focus when the user clicks on a window. Under macOS this is deactivated. You can activate it for all X11 applications by typing in the terminal:

       defaults write wm_click_through -bool true

When compiling GTK-related software, you need to add two lines to the fpc.cfg file, to enable use of libraries:


Required software

  • Install Apple´s X11, available on your Installation Disk.

For Jaguar 10.2.x you can download X11 on source forge at the X11 on Mac Project.

For Panther 10.3.x (but not for any other version!) also at Apple.

For Tiger 10.4 you must install X11 from your tiger DVD. This is to be able to display X11 programs. Tip: Drag the X11-Icon from /Applications/Utilities/X11 into the Dock for convenient starting.

  • Install Apple´s XCode, available on your Mac Installation Disk or at Apple Developer Connection (requires creation of account, but the free online program is enough). This installs the XCode IDE and all the developer stuff.
  • Install fink, available at Sourceforge. This is a Mac 'apt-get'esque package system.
  • Check if installation was successful, open a Terminal and type:
 echo $PATH

This should give you:


  • After successfull installation of the above, open a Terminal and type:
sudo apt-get update
sudo apt-get install glib glib-shlibs gtk+-shlibs gdk-pixbuf gdk-pixbuf-shlibs

This installs GTK.

If you decide not to use Fink or if your Fink installation is customized

If you install gdk-pixbuf, gtk, and glib libraries not using Fink, or if your Fink installation is customized to install under other than /sw directory, then make sure that the environment variable DYLD_LIBRARY_PATH point to where the libraries are. For instance, it you use MacPorts, the command below should do the trick:


The environment variable should be setup every time before running lazarus, or should be run from shell startup script.

How to get going

  • Start X11.
  • You get your XTerm. Focus it and type
cd /usr/local/share/lazarus/

Lazarus as Icon

You can drag and drop the X11 app onto your dock to have a one-click way of starting X11.

To simplify starting Lazarus, in X11, choose Applications | Customize Menu, then click Add. Under Menu Name enter Lazarus, under Command enter the following:


Click Done to close. Now you can start Lazarus from X11 simply by choosing Applications | Lazarus.

BEWARE: if you use the below svn, then use

 open -a /Users/yourname/pascal/lazarus/lazarus