The form element "select" in forms of Tiki Forum and in other features of Tiki is missing the term (selector) "custom-select" as part of the CSS class to render it correctly in the Bootstrap theme design.
Making this simple change would greatly improve and unify the UI of Tiki with the currently available Themes.
See attached screen shot of added term in inspector for Tiki Forum feature.
To help developers solve the bug, we kindly request that you demonstrate your bug on a show2.tiki.org instance. To start, simply select a version and click on "Create show2.tiki.org instance". Once the instance is ready (in a minute or two), as indicated in the status window below, you can then access that instance, login (the initial admin username/password is "admin") and configure the Tiki to demonstrate your bug. Priority will be given to bugs that have been demonstrated on show2.tiki.org.