The object browser is a drilldown widget for probing the values of model variables. Since model variables are implemented as TCL commands, this tool lists all TCL commands. Commands containg a ``.'' in their name belong to objects, so these commands are grouped and labelled in blue. TCL namespaces are grouped and labelled in green. Clicking on this blue group opens another window containing just that group of commands. Clicking on a green name drills down into a namespace. Clicking on a red command runs it, and the result is displayed next to it -- if this is a Tcl_obj instance variable, the result is the value of the variable. You can specify an argument to the command in the Args input box.
Shift clicking allows you to select a range of commands to execute, and Control clicking allows a non-contiguous selection to be made. This is more useful for the Repeat option, which repeats the selected commands every second, allowing you to dynamically follow a model's variables.
Right mouse click on any item brings up a menu of options.