kcms/desktop: Expand button label from "Add" to "Add Desktop"
To address concerns about being misinterpreted as "Add Row", given that it now sits right next to the " Rows" spinner.
Follow-up to MR !5572 (merged). This comment on Nate's blog brings up some valid points and I encourage any reviewer to read it before continuing with this MR. Their preferred option is to simply keep the row count spinner in the options section below, whereas I still prefer keeping it in the header because:
- Changing the number of rows affects the contents of the list view, and if the row count spinner were at the bottom then it would affect controls further up. Which isn't ideal.
- Keeping the spinner at the bottom right of the list view, where it was before, would look even weirder than it was before without the "Add" button providing balance on the left side. The straightforward alternative would be to embed it into the main options form, but that needs an extra label for something that I think is quite self-explanatory with just the control itself.
- Space savings may not affect tons of people, but still matter for some and make the KCM tidier.
So I'll go with an "Add Desktop" one-liner in this MR instead.