I am using kee and Firefox 59.0.1 64bit on Win7pro.
However, the display of some sites disappears.
For example, it is TOP page of Google.
When the mouse cursor passes through it is displayed if it is Link.
And as a result of searching for “test”, for example, it becomes white.
I reinstalled firefox to the whole new, but the situation does not change.
Even if I disable Kee, the situation will not change. Deleting Kee will solve this problem.
Where is the problem?
Before firefox was updated, it worked without problems.
It’s not clear to me exactly what problem you are describing but if disabling Kee does not alter the situation, it is unrelated to Kee.
It sounds as though you have found a bug in Firefox 59 so you could ask for help from them in order to narrow down what the cause of the problem is so that they can fix it in a future version.
That must be a bug in Firefox or your graphics card drivers. Kee does not have that level of control over what is displayed on the screen.
Try updating your graphics (display) drivers first and then look for help from the Firefox support forum - it is possible that there is an advanced setting somewhere in Firefox that you can change to make the problem go away temporarily while they work on a final fix for the issue.
If Kee is the only add-on you have installed, it is possible that Firefox is changing some settings or behaviours when you (un)install it so that detail could be worth mentioning when you describe the problem to the Firefox support team.