Hi Christophe,
The GTTools only work properly in Pharo 3.
The inspector and the playground will soon be integrated into Pharo 4.
Right now you can load them using the following script (but that will change very soon).
The GTDebugger does not work for the moment in Pharo 4.
Gofer new smalltalkhubUser: 'Moose'
project: 'GToolkit';
package: 'ConfigurationOfGTInspector';
load.
Gofer new smalltalkhubUser: 'Moose'
project: 'GToolkit';
package: 'ConfigurationOfGTPlayground';
load.
(((Smalltalk at: #ConfigurationOfGTInspector) project version: '0.1-baseline')) load: #('Core' 'Tests').
(((Smalltalk at: #ConfigurationOfGTPlayground) project version: '0.1-baseline') load) .
(Smalltalk globals at: #GTInspector) registerToolsOn: Smalltalk tools.
(Smalltalk globals at: #GTPlayground) registerToolsOn: Smalltalk tools.
Cheers,
Andrei