onMouseDown

gistfile1.js

onButtonDown = function(event)
{
	event.result = [
		  ["save", "enabled", false],
		  ["Pass", "enabled", false],
		  ["save", "label", waitingFrase()]
	];
}

onButtonClick = function(event){
	setup.password = event.currentValues.Pass;
	var appDir = fw.userJsCommandsDir + "/my_commands";
	var file = appDir+"/buildUp.jsf";
	fw.runScript(file);
}

panelJSON = {
	events: {
		onFwObjectSettingChange: function(event) {
			console.log(":::: onFwObjectSettingChange");
		},
		onFwActiveToolChange: function(event) {
			console.log(":::: onFwActiveToolChange");
		}
	},

	children: [
		{ TextInput: {
			name: "Pass",
			toolTip: "Choose a password",
			text: "clientpass",
			style: {
				fontWeight: "bold",
				fontSize: 15,
			}
		} },
		{ Button: {
			label: "Build Presentationx",
			name:"save",
			events: {
				buttonDown: onButtonDown,
				click: onButtonClick
			}
		} }
	]
};

fwlib.panel.register(panelJSON);

You could also try calling validateNow() on the changed controls to force an update:

event.result = [
      ["save", "enabled", false],
      ["Pass", "enabled", false],
      ["save", "label", waitingFrase()],
      ["save", "validateNow"],
      ["Pass", "validateNow"]
];

events: {

            buttonDown: function(event){
                event.result = [
                ["save", "label", "Exporting..."],
                ["Pass", "enabled", false]
                // ["save", "enabled", false]
                ];

            },

            click: function(event)
            {



                event.result = [
                ["save", "label", "Export Case"],
                ["save", "enabled", true],
                ["Pass", "enabled", true]
                ];

                setup.password = event.currentValues.Pass;
                fw.runScript(fw.userJsCommandsDir+"/case2/buildUp.jsf");

            }
        }