In 4 there was a floating element dialogue. In 5 there just seems to be the View Elements side-bar. I find this much harder to navigate. Can the floating dialogue be resurrected?
No, the old Elements dialog has been replaced. The navigations works similar to the old dialog. In the old dialog you have to choose first the category in the upper part by clicking on an icon. Now you have to choose the category from a drop-down list. That is different, but not more difficult. In the old dialog you then click on the desired element. Now you do the same, click on the desired element.
The new pane provides better presets in the “Operator” category, has an additional category for examples and has the extended color attributes. There could be more examples, I miss matrices e.g., but I think the new way is more suitable for beginners. Experienced users of Math will not use the Elements anyway. They type the commands directly or get them from the context menu.
If you like to have the new pane floating, that is no problem. Simple drag it away.