increase size and width of tool tip extjs 4.1

[surajan]

					{
						xtype: 'button',					


						iconCls:'question',
						tooltip:"<b>read-only</b>:Read-only users will have read only access to all            pages<br>s ",
						padding: '2 6 2 7'
						
						
					}

I need help in increasing the height and size of my tool tip.. I am unable to do so. setting the width and height only increases the size of the button.

[mitchellsimoens]

tooltip can accept a config object also