Fix resize-handle visability for vertical layout (mobile)

[light-and-ray]

Description

• a simple description of what you're trying to accomplish
• a summary of changes in code
• which issues it fixes, if any

Screenshots/videos:

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Checklist:

• I have read contributing wiki page
• I have performed a self-review of my own code
• My code follows the style guidelines
• My code passes tests

[AUTOMATIC1111]

Shouldn't that be inside the if block? And the handle should be referred to as R.handle instead of parent.querySelector('.resize-handle').

[light-and-ray]

R.handle can be null if resize window and don't touch resize handle. And how you see it inside if block? We don't need to check grid template for that and also we need to have this if-else inside displayResizeHandle

[light-and-ray]

The name displayResizeHandle looks like it shouldn't change anything, I agree. But it already changes style and opacity, maybe it should be renamed

And also maybe I should remove R.handle at all, and init new parent's field inside setup function

[AUTOMATIC1111]

Like this:

            if (R.handle != null) {
                R.handle.style.display = "none";
                R.handle.style.opacity = '0';
            }

[light-and-ray]

As I thought, it doesn't work. Also R is global for every parent, it contains handle which is being resized right now

I updated PR, check it. I think it's better now