var buttons;
var buttonsPreloaded = false;

function preloadButtons() {
	if (!document.images ) { return; }

	buttons = new Array();

	/* main navigation */
	buttons["about"] = new Object();
	buttons["about"].normal = new Image(111, 30);
	buttons["about"].normal.src = "images/navigation/level1/about_off.gif";
	buttons["about"].hover = new Image(111, 30);
	buttons["about"].hover.src = "images/navigation/level1/about_on.gif";

	buttons["services"] = new Object();
	buttons["services"].normal = new Image(103, 30);
	buttons["services"].normal.src = "images/navigation/level1/services_off.gif";
	buttons["services"].hover = new Image(103, 30);
	buttons["services"].hover.src = "images/navigation/level1/services_on.gif";

	buttons["sectors"] = new Object();
	buttons["sectors"].normal = new Image(103, 30);
	buttons["sectors"].normal.src = "images/navigation/level1/sectors_off.gif";
	buttons["sectors"].hover = new Image(103, 30);
	buttons["sectors"].hover.src = "images/navigation/level1/sectors_on.gif";

	buttons["projects"] = new Object();
	buttons["projects"].normal = new Image(114, 30);
	buttons["projects"].normal.src = "images/navigation/level1/projects_off.gif";
	buttons["projects"].hover = new Image(114, 30);
	buttons["projects"].hover.src = "images/navigation/level1/projects_on.gif";

	buttons["contact"] = new Object();
	buttons["contact"].normal = new Image(120, 30);
	buttons["contact"].normal.src = "images/navigation/level1/contact_off.gif";
	buttons["contact"].hover = new Image(120, 30);
	buttons["contact"].hover.src = "images/navigation/level1/contact_on.gif";

	/* about us sub-navigation */
	buttons["history"] = new Object();
	buttons["history"].normal = new Image(124, 18);
	buttons["history"].normal.src = "images/navigation/level2/history_off.gif";
	buttons["history"].hover = new Image(124, 18);
	buttons["history"].hover.src = "images/navigation/level2/history_on.gif";

	buttons["management_team"] = new Object();
	buttons["management_team"].normal = new Image(124, 18);
	buttons["management_team"].normal.src = "images/navigation/level2/management_team_off.gif";
	buttons["management_team"].hover = new Image(124, 18);
	buttons["management_team"].hover.src = "images/navigation/level2/management_team_on.gif";

	buttons["careers"] = new Object();
	buttons["careers"].normal = new Image(124, 18);
	buttons["careers"].normal.src = "images/navigation/level2/careers_off.gif";
	buttons["careers"].hover = new Image(124, 18);
	buttons["careers"].hover.src = "images/navigation/level2/careers_on.gif";

	/* about us careers sub-navigation */
	buttons["career_opportunities"] = new Object();
	buttons["career_opportunities"].normal = new Image(145, 18);
	buttons["career_opportunities"].normal.src = "images/navigation/level3/career_opportunities_off.gif";
	buttons["career_opportunities"].hover = new Image(145, 18);
	buttons["career_opportunities"].hover.src = "images/navigation/level3/career_opportunities_on.gif";

	buttons["students"] = new Object();
	buttons["students"].normal = new Image(145, 18);
	buttons["students"].normal.src = "images/navigation/level3/students_off.gif";
	buttons["students"].hover = new Image(145, 18);
	buttons["students"].hover.src = "images/navigation/level3/students_on.gif";

	/* sectors sub-navigation */
	buttons["healthcare"] = new Object();
	buttons["healthcare"].normal = new Image(144, 18);
	buttons["healthcare"].normal.src = "images/navigation/level2/healthcare_off.gif";
	buttons["healthcare"].hover = new Image(144, 18);
	buttons["healthcare"].hover.src = "images/navigation/level2/healthcare_on.gif";

	buttons["recreation"] = new Object();
	buttons["recreation"].normal = new Image(144, 18);
	buttons["recreation"].normal.src = "images/navigation/level2/recreation_culture_off.gif";
	buttons["recreation"].hover = new Image(144, 18);
	buttons["recreation"].hover.src = "images/navigation/level2/recreation_culture_on.gif";

	buttons["corrections"] = new Object();
	buttons["corrections"].normal = new Image(144, 18);
	buttons["corrections"].normal.src = "images/navigation/level2/corrections_off.gif";
	buttons["corrections"].hover = new Image(144, 18);
	buttons["corrections"].hover.src = "images/navigation/level2/corrections_on.gif";

	buttons["laboratory_research"] = new Object();
	buttons["laboratory_research"].normal = new Image(144, 18);
	buttons["laboratory_research"].normal.src = "images/navigation/level2/laboratory_research_off.gif";
	buttons["laboratory_research"].hover = new Image(144, 18);
	buttons["laboratory_research"].hover.src = "images/navigation/level2/laboratory_research_on.gif";

	buttons["corporate_education"] = new Object();
	buttons["corporate_education"].normal = new Image(144, 18);
	buttons["corporate_education"].normal.src = "images/navigation/level2/corporate_education_off.gif";
	buttons["corporate_education"].hover = new Image(144, 18);
	buttons["corporate_education"].hover.src = "images/navigation/level2/corporate_education_on.gif";

	/* projects sub-navigation */
	buttons["renowned"] = new Object();
	buttons["renowned"].normal = new Image(113, 18);
	buttons["renowned"].normal.src = "images/navigation/level2/renowned_off.gif";
	buttons["renowned"].hover = new Image(113, 18);
	buttons["renowned"].hover.src = "images/navigation/level2/renowned_on.gif";

	buttons["awards"] = new Object();
	buttons["awards"].normal = new Image(113, 18);
	buttons["awards"].normal.src = "images/navigation/level2/awards_off.gif";
	buttons["awards"].hover = new Image(113, 18);
	buttons["awards"].hover.src = "images/navigation/level2/awards_on.gif";

	buttons["sector_specific"] = new Object();
	buttons["sector_specific"].normal = new Image(113, 18);
	buttons["sector_specific"].normal.src = "images/navigation/level2/sector_specific_off.gif";
	buttons["sector_specific"].hover = new Image(113, 18);
	buttons["sector_specific"].hover.src = "images/navigation/level2/sector_specific_on.gif";

	buttons["view_all"] = new Object();
	buttons["view_all"].normal = new Image(113, 18);
	buttons["view_all"].normal.src = "images/navigation/level2/view_all_off.gif";
	buttons["view_all"].hover = new Image(113, 18);
	buttons["view_all"].hover.src = "images/navigation/level2/view_all_on.gif";

	/* projects sector-specific sub-navigation */
	buttons["proj_healthcare"] = new Object();
	buttons["proj_healthcare"].normal = new Image(149, 18);
	buttons["proj_healthcare"].normal.src = "images/navigation/level3/healthcare_off.gif";
	buttons["proj_healthcare"].hover = new Image(149, 18);
	buttons["proj_healthcare"].hover.src = "images/navigation/level3/healthcare_on.gif";

	buttons["proj_recreation_culture"] = new Object();
	buttons["proj_recreation_culture"].normal = new Image(149, 18);
	buttons["proj_recreation_culture"].normal.src = "images/navigation/level3/recreation_culture_off.gif";
	buttons["proj_recreation_culture"].hover = new Image(149, 18);
	buttons["proj_recreation_culture"].hover.src = "images/navigation/level3/recreation_culture_on.gif";

	buttons["proj_corrections"] = new Object();
	buttons["proj_corrections"].normal = new Image(149, 18);
	buttons["proj_corrections"].normal.src = "images/navigation/level3/corrections_off.gif";
	buttons["proj_corrections"].hover = new Image(149, 18);
	buttons["proj_corrections"].hover.src = "images/navigation/level3/corrections_on.gif";

	buttons["proj_laboratory_research"] = new Object();
	buttons["proj_laboratory_research"].normal = new Image(149, 18);
	buttons["proj_laboratory_research"].normal.src = "images/navigation/level3/laboratory_research_off.gif";
	buttons["proj_laboratory_research"].hover = new Image(149, 18);
	buttons["proj_laboratory_research"].hover.src = "images/navigation/level3/laboratory_research_on.gif";

	buttons["proj_corporate_education"] = new Object();
	buttons["proj_corporate_education"].normal = new Image(149, 18);
	buttons["proj_corporate_education"].normal.src = "images/navigation/level3/corporate_education_off.gif";
	buttons["proj_corporate_education"].hover = new Image(149, 18);
	buttons["proj_corporate_education"].hover.src = "images/navigation/level3/corporate_education_on.gif";

	/* all done */
	buttonsPreloaded = true;
	return;
}

function switchButton(buttonName, buttonState) {
	if (!document.images) { return; }
	if (!buttonsPreloaded) { return; }
	if (!buttonName || buttonName == "") { return; }
	if (!buttonState || buttonState == "") { return; }

	if (document.getElementById) {
		var target = document.getElementById(buttonName);
	} else if (document.all) {
		var target = document.all(buttonName);
	} else if (document.layers) {
		var target = document.images[buttonName];
	}

	if (target) {
		target.src = eval("buttons['" + buttonName + "']." + buttonState + ".src");
	}

	return;
}