[4.1.0] Grid with Empty String Columns Displays, Didn't in 4.0.7

[ZachG]

REQUIRED INFORMATION\
Ext version tested:

• ExtJS 4.1.0

Browser versions tested against:

• Chrome

Description:

• I have a grid with two columns, and their text is the empty string.
• In 4.0.7, using the empty string made the column headers hidden.
• In 4.1.0, the column headers are small but still visible.

Steps to reproduce the problem:

• Run the code below in 4.0.7 and 4.1.0.

The result that was expected:

• It would look like 4.0.7

The result that occurs instead:

• Nope

Test Case:

Ext.create("Ext.window.Window", {
	width:500,
	height:500,
	layout:"fit",
	items:[
		{
			xtype:"grid",
			store:{
				proxy:{
					type:"memory",
					reader:{
						type:"json"
					}
				},
				model:Ext.define("MyModel", {
					extend:"Ext.data.Model",
					fields:["a", "b"]
				}) && "MyModel"
			},
			columns:[
				{
					text:"",
					dataIndex:"a"
				},
				{
					text:"",
					dataIndex:"b"
				}
			]
		}
	]
}).show();

[mitchellsimoens]

You can actually make sure the header container is hidden by specifying the columns as a config of the header container:

columns : {
    hidden : true,
    items  : [
        {
            text      : "",
            dataIndex : "a"
        },
        {
            text      : "",
            dataIndex : "b"
        }
    ]
}

[evant]

Or alternatively use the hideHeaders config on the grid. This was actually a bug in 4.0.x, the header should always show up if it's not configured with hidden: true.