wemmc I noticed two things that I find concerning.
OpenLP 3.0.2 takes almost twice as long to start as the version we were using (2.4.x)the icon pack is ugly and doesn't look like the task that it's supposed to do. e.g. the icon for blank to theme doesn't look anything like blanking to theme, and the blank to desktop has an X through it. Why? it doesn't make any sense, and seems like a massive step backwards in usability. How am I supposed to explain what it means to the less tech knowledgeable users? Who thought this was better?
I'm a very occasional user of OpenLP and have only just downloaded 3.0.2 after using 2.4.6.
I use the portable versions and find no noticeable difference between the two for startup times.
I know it's been a few months since you posted and I hope you're used to the new icon pack by now and have made some sense of it.
I don't have any problem with the "show theme" icon. It's a very standard image icon used in many software packages, including this forum, and what is a theme but the image shown behind any text being presented.
Similarly, with the the "Show Desktop" icon, an "X" is about as standard as you can get for "don't" or "close" and it in this case it says don't show, or close, the OpenLP window.
I even actively prefer the vertically oriented Previous and Next icons in the new version, as that's the direction you move objects in in the lists above. And the new icons for Preview (with a blank row of seats in front of the screen) and the Live (with an audience seated in front of the screen) seem , just right to me.
About the only icon that is a bit "techie" is the multi-platter hard disk icon that is used to indicate a database. That's even more old fashioned than 1980s the 3.5" floppy disk icon still common to indicate "Save" in almost every software package. But a database is what you need to have in mind when trying to find a symbol to represent "Maintain the list of authors, topics, and books".