The goal here is to make the meaning of button colors in Tiki more intuitive and consistent. In the Bootstrap update to version 4, part of Tiki 19, some button class names and default colors have changed from Bootstrap 3. (See https://getbootstrap.com/docs/4.0/components/buttons/ .) The meanings conveyed by button colors may not be as clear now as they were in Bootstrap 3, when the default button color was essentially neutral and colors were used for special meaning and, even with Tiki and Bootstrap 3, there wasn't a clear pattern of button color use.
For this reason, the button classes are being organized in the .tpl files, etc. and will be in the HTML and they will be most apparent in the Default Bootstrap theme. Other themes, of course, can style buttons as they please but the hope is that the organization of button colors makes sense and will benefit themes and users even if the themes' palettes vary from the Bootstrap default.
One suggestion is that sites could assign an admin theme that shows the button colors most clearly, and another site theme with perhaps less obvious colors that are toned down from the default ones.
Button purpose category | Class and default color | Examples |
Make a significant change | btn-primary (blue) | Save, Apply, Rename, Select, Attach |
Confirmation for non-destructive change | btn-success (green) | Anti-CSRF confirmation |
Make a destructive change | btn-danger (red) | Delete |
Confirmation for destructive change | btn-warning (yellow) | Are you sure? |
Display information | btn-info (cyan) | History, Source, Preview, Find |
Make an insignificant change | btn-secondary (gray) | Tabs/No tabs, Sort, Filter |
Dev mailing list discussion starts here: https://sourceforge.net/p/tikiwiki/mailman/message/36346433/