I checked the PlugInIntf.pas for new functions.
I relaised, that the PL/SQL Developer 15 is shipped with a file, wich is dated back to 2015, and many new functions does not exists.
But, as I compared the two files, it looks, that some new functions are exists in that file, which is not in the previous.
For example, ide_getcurrentsytle

Left file is from the PL/SQL Developer14 folder, right side is the 15 version.

The PlugInDoc\Interface\PlugInIntf.pas file is from March 29, 2022 and is up-to-date. Can you verify?

Yes, the date of the file is March 29, 2022.
But the contents of the file looks like it is 2015, but not exactly, because there are new parts in the file, which are not exists in the 2020 version, but some parts are missing.
I mean the 2020 version is the file which was installed with PL/SQL Developer 14 .

For version 15.0.3 file c:\Program Files\PLSQL Developer 15\PlugInDoc\Interface\PlugInIntf.pas is still buggy.

For example, the functions SQL_SetPlugInSession, IDE_GetMenuItemLayout (and many others) from the documentation are missing.

Function IDE_GetBrowserUser is not assigned.

Sorry for necroposting, but I've installed v.15 just now.
IDE_GetBrowserUser() is 179, and seems it may have a return value, but I'm too lazy to dump&research it now

Marco, please add a description on these functions: 179 (IDE_GetBrowserUser), 290, 291. We see them in RegisterCallback()