I've noticed that on some dashboards (all Simple XML dashboards), I'll have an extra button that says "Move Panels". When I click it, I'll get a box that lets me click-and-drag small square boxes with the panel types/names around, and then it'll update the page.
On most dashboards, I can hover over a dashboard panel, causing it to highlight, and it lets me click and drag it around.
In most cases though, I actually prefer the "Move panels" button. Clicking and dragging the panels with the charts/graphs in them tends to be terribly slow and CPU intensive on the browser.
I'm just curious what is triggering some of them to behave one way, and others another way.
I've noticed that too. I've narrowed it down to cases where the base XML includes non-default options for the visualization. For instance, with a simple chart and there may be a need to modify the baseline for the simple XML so that the colours match the description of the fields at play. When we turn on the edit you can appreciate the fact that we are able to move the visualization with the mouse.
In this case we would like to include a simple option: