Fix sorting problem clean

[zhizhangchen]

No description provided.

[grgustaf]

Let's talk about this today so I understand what it's solving, so I can at least test.

By the way, I'm not sure if you did this here, but probably the best practice when we have to override a jQuery function would be this:

• First check in a patch that directly copies the function from jQuery.
• Second check in a patch that reformats the whitespace to match our coding style.
• Finally check in any changes that we make to the function.

This would allow us to do diffs against the second patch to see the modifications we've made.

[zhizhangchen]

This patch solved the following problems:

1. Placeholder jittering when sorting in a button group.
   a) Open a new project and drag a Button Group into layout view
   b) Drag the first button in the Button group down slowly
   c) Notice that there’s much jittering of the placeholder when the dragging button is over the last button.
2. Can’t place a button between a footer and a button group when sorting upwards.
   a) Open a new project and drag a Button Group into layout view
   b) Drag a button in the Button group down to the footer and then up to try to put it between the Button Group and Footer
   c) Notice that the button jumps into the Button Group instead of between the Button Group and the footer
3. When dragging at the bottom of a button, it can’t be placed between a Header and a button group.
   a) Open a new project and drag a Button Group into layout view
   b) Drag a button with mouse pointer near the bottom of the button in the Button group up to the Header and then down to try to put it between the Button Group and the Header
   c) Notice that the button jumps behind the Button Group instead of between the Button Group and the header
4. Can’t drag a button in header between the header and Button group
   a) Open a new project, drag a Button Group into layout view, a button in Header
   b) Drag the button in header down to try to put it between the Button Group and the Header
   c) Notice that the button jumps behind the Button Group instead of between the Button Group and the header
5. Sorting problem when there’s a button between two button groups.
   a) Open a new project, drag two Button Groups and a button between them into the layout view
   b) Drag a button in the upper button group down and then up to try to place it between the lower button group and the button.
   c) Notice that the placeholder jitters when dragging through the button and the placeholder jumps to the place between the button and the upper the Button Group when dragging upwards.
6. Can't position a Collapsible within an Accordion
7. Hysteresis issue when sorting Collapsibles
8. Can’t drag a button from palette between a Button Group and a Footer
   a) Open a new project, drag a Button Group into layout view
   b) Drag a button from the palette and try to put it between the Button Group and the Footer
   c) Notice that the button can’t be placed between the Button Group and the Footer

[grgustaf]

It's a vast improvement, thank you.

It would be nice if we could figure out a way to keep button groups drawn tightly together, rather than split apart. Or is that integral to the solution? They look weird this way.

Also, the extra space inside Button Groups leads to a weird effect: if you click between the buttons, you select the Button Group, which you can do accidentally when aiming for a Button. This shows the first button with a blue glow, which is confusing. I think I filed an issue elsewhere on that.

Merged.