Salesforce open Simple Dialog in custom button/link or on a visualforce page

gistfile1.js

// if you want to use it inside a visualforce page create a function around it
//function showFollowUp() {
// if you want to use it in a button make sure you require jQuery
// {!REQUIRESCRIPT("https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js")} // UNCOMMENT IF IN A BUTTON
{!REQUIRESCRIPT("/soap/ajax/29.0/connection.js")}
{!REQUIRESCRIPT("/soap/ajax/29.0/apex.js")}

// get the dialog with your dialog name
var d = sfdcPage.dialogs['MyCoolDialog'], close;
if (!d) {

	// if the dialog doesn't exist create one
	d = sfdcPage.dialogs['MyCoolDialog'] = new SimpleDialog('MyCoolDialog'+Dialogs.getNextId(), false);
	// set general information on your dialog and finally run the create function
	d.setTitle('Change Status');
	d.setWidth(600);
	d.createDialog();
	d.allowKeyboardEsc = true;

	sforce.apex.execute("CaseTaskButtonController","getButtonContent",{page: "ButtonContent"},
		{
			onSuccess:function(result) {
				console.log(result);
				d.setContentInnerHTML(result);
			},
			onFailure: function(error) {
				alert(error);
			}
		}
	);
	
	// we also need to make sure we have a close button on the dialog
	if ($(d.dialog).find('#InlineEditDialogX').size() == 0) {
		// if there is none we create it
		close = $('<a id="InlineEditDialogX" title="Close" tabindex="0" href="javascript:void(0)" class="dialogClose">Close</a>');
		// add some functionality to the close button - for the default ui we change the classname on mouseover/out
		close.mouseover(function() {
			this.className = 'dialogCloseOn';
		}).mouseout(function() {
			this.className = 'dialogClose';
		}).click(function() {
			// finally our on click handler which closes the dialog
			d.hide();
		});
		// insert the new generated close button before the h2 tag so it'll show up on the top right corner
		close.insertBefore($(d.dialog).find('.topLeft h2'));
	}
}

// now it's time to show the new dialog
d.show();
//}