Oh, a case of not fully RTFM on my side. I stopped reading at “sailjail”, because I was not interested in technical details. Thus I suggest to alter the description to:
Shows when packages have been installed or removed.
This app integrates itself into SailfishOS’ Settings app with a new entry there.<br />
This is necessary in order to read the zypper install log, due to SailJail.
Unfortunately, all I see there on my XperiaX@SFOS3.2.1 with install-history 0.9.7 is:
Could not load page
I will look at the library, although atm almost all of my apps including this one are QML only without C++ parts.
Oh, sorry, then only the QML stuff there may be useful for you in general, but most likely not for install-history.
BTW, IMO it also is interesting to be able to determine when repositories have been added or removed. This information also seems to be recorded in that log file.