Given a simple (non-tabular) long list of small items, have studies shown a strong reason to prefer vertical vs. horizontal flow/wrapping of those items when displayed in a single 'field'?
I'm working on a project where we plan to have a progress meter on a dashboard screen which corresponds to a set of numbered tasks. (These tasks are performed on books, by chapter. The chapters don't have titles, so we just show the numbers.) Most of the time, the tasks will be done in order, but sometimes teams will split the work up and do it non-sequentially, so this popup provides a way to break things down specifically. (It's inspired by Gmail's label-applying feature. The field is modeled after a typical Print dialog's page-specifying field.)
I'd usually expect to see a list of objects wrap vertically, like this:
1 6 11 2 7 12 3 8 13 4 9 14 5 10 15
But here they are wrapping horizontally in order to roughly match the direction of the progress meter that they control. (Most books, but not all, have more than five chapters.) Is there a good rule of thumb to use here?
The initial state:
Side question: Most of the time, the popup is not needed, as the "+" button should suffice for checking off the next not-yet-complete chapter, or the checkbox can check off the entire book. Any thoughts as to whether those "+ -" buttons should be disabled when gaps between ticks make it hard to guess what they would do? (See second image above.)
There would probably be an Undo button at the top of the main screen, e.g. to use if you clicked the main check box and blew away a complex mix of ticks.