BUG #15097: pgadmin3 tabs not properly themed with wxGTK3

The following bug has been logged on the website:

Bug reference:      15097
Logged by:          Pierre-Yves
Email address:      kyrios@skynet.be
PostgreSQL version: Unsupported/Unknown
Operating system:   x86_64 GNU/Linux - 4.15.7
Description:

We are outphasing wxWidgets GTK2 build and we have been reported that the
tabs in pgadmin3 (which remains very popular) aren't themed properly when
wxGTK3 is used.

See below screenshot; unstable is the wxGTK3 build.

https://dev.solus-project.com/file/data/jzugkmqtn5ikapyg6p2o/PHID-FILE-3gp2fiwycdzejhjcy3pq/pg-c.png

Thank you!