Image viewer: Incorrect description of color settings and strange check box

[skyper]

This is a follow-up of #21062:

Additionally, the tooltip of the button is incorrect Change visibility of selected layer and I don't know what the "Layer" checkbox is about as there is no tooltip and for me it is always unchecked and clicking on it does not change anything.

What steps will reproduce the problem?

1. Have a geoimage layer
2. Open image viewer
3. Hoover the mouse over the color setting button
4. Carefully read the tooltip
5. Click on the button
6. Hoover the mouse over the three settings an carefully read the tooltips
7. Click on the layer checkbox

What is the expected result?

Proper description in the tooltip with subject "image", some tooltip about the "layer" checkbox and some action clicking on the checkbox

What happens instead?

Subject is "layer" instead of "image", no tooltip for the checkbox which is not working at all

Please provide any additional information below. Attach a screenshot if possible.

Relative:URL: ^/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2021-07-12 02:41:41 +0200 (Mon, 12 Jul 2021)
Revision:18004
Build-Date:2021-07-12 00:42:49
URL:https://josm.openstreetmap.de/svn/trunk