This is a great effort!
Everything worked for me except the cross-install from Linux64 -> Linux32 (which is a problem I have with a regular install on my system - Puppy Linux 64-bit)
Some suggestions for the GUI (tested in linux):
The main window title could be 'Lazarus and Freepascal installer and updater'
The buttons [Start fpcup, fpc only ] and [Start regular fpcup] would be better labelled
[Install or update fpc] and [Install or update Lazarus] I think.
For first time use,
1. An information dialog at startup would be handy. The GUI looks overwhelming for a beginner running it for the first time.
2. (Linux) After installing Lazarus, an info dialog showing how to run Lazarus (e.g. location of startlazarus) or.. Is it possible to make a desktop icon?
2a. or.. Maybe even a button to start Lazarus from your GUI
The scrolling textwindow - does it always need to be shown, or could it be an option? For a beginner, it's not really useful other than to show that something is happening.
A simple modal dialog showing the action in progress (i.e. Downloading, Copying files, Installing etc) would look better and be just as useful. (I did spot the labels, but a dialog looks more.. GUI-like)
Would it be possible to capture only error messages to a logfile, so that the user could have a better idea of what went wrong?
The group of buttons at the bottom: Could the group panel have the caption 'Install or Update'?
I hope you don't mind me giving unasked-for suggestions!
I am already loving this utility
Once all the bugs are out, the Lazarus team should consider including this on their main page IMO. fpcupdeluxe is a country mile better than their regular installer. Perhaps it could be offered as the 'Advanced installer and Updater'?