Mr B

Agreed. And when I click “Hide Image” I’m getting a big white box with a black border… I clicked “hide” not “show a big white square with a black border” :-/

— In summary: —
* if height is zero : I cannot upload a new header image (occurs in twentyeleven theme too, even with all plugins disabled)
* if the height isn’t zero : when I hide the header image the result is an ugly box on the screen

— Workaround —
OK my workaround for this issue is to upload a blank header image and set the header height to a really small number, but leave it flexible:

$defaults = array(
	'flex-height'            => true,
	'flex-width'             => false,
	'width'                  => 957,
	'height'                 => 15  # Can't upload header images if zero *cry*
);
add_theme_support( 'custom-header', $defaults );

NOW my users can choose to have a header image / or a blank header image / or upload their own.

I wouldn’t mind just setting the height to 100, *however* in many cases we will desire no header image at all, and in that case it puts a big ugly white square with a border when I use the ‘Hide image’ button (Appearance > Header image > Hide image)

Yes, deactivated all plugins.

I tried setting image height to 1 in functions.php.. Looks like the crop selection area is off screen / in an area I cannot click. Same thing happens if height is left unspecified in functions.php:

$defaults = array(
	'width'                  => 500
);
add_theme_support( 'custom-header', $defaults );

Meanwhile add the height back into functions.php and the image cropper starts working again:

$defaults = array(
	'width'                  => 500,
	'height'                 => 100
);
add_theme_support( 'custom-header', $defaults );

?? Yeh I wasn’t being clear there, my apologies. So the image cropping screen comes up with the selected image, however I cannot select / drag / crop the image (and no portion of the image is selected). If the dimensions are wrong then there is no “skip” option. Clicking the “Crop Image” button results in the error “There has been an error cropping your image.” .. and this is presumably because no crop area is specified (and obviously I cannot specify one)

I said: “index.php for my template looks like this:”..
Should’ve said: index.php for my *theme* looks like this:” …

Running: WordPress 4.2.2 (not 3.0)