This add-on is discontinued and will not receive any updates for Thunderbird 68+. I neither have the time nor the will to rewrite the add-on for TB 68+. Mozilla devs lied (again or like always) when they said, there won't be changes in add-on environment on Thunderbird.
CustomCSSforTb will take over Thunderbird 68+ support. Most CSS files still work in Thunderbird 68.
CustomizeMyBird v2.0+:
Github (download and changelog): https://github.com/Aris-t2/CustomizeMyBird/
ATN aka AMO: https://addons.thunderbird.net/addon/customizemybird/
CustomizeMyBird add-on offers ui tweaks to improve Thunderbirds appearance and usability.
Features
- Tabs: switch between default tabs and classic squared tabs (+ Aero blue colors)
- Tabs: custom height
- Tabs: custom border roundness
- Tabs toolbar: hide Lightning buttons
- Tabs and tab toolbar buttons: switch positions (Windows/Linux)
- Main menubar: above/below tabs toolbar (Windows/Linux)
- Main menubar: compact view (Windows/Linux)
- Mein menubar: Aero blue colors
- Main toolbar: compact view
- Toolbars: default colors / Aero blue colors
- Statusbar: hide status bar
- Quick-filter-bar: move below mail list (if visible)
- Attachments: move above mail content (if visible)
- Attachments: move buttons to start position (if visible)
- Main menu button alternative appearance: customizable colors, text, icons
- Add-ons Manager: alternative appearance (+ Aero blue colors)
- Add-ons Manager: compact view
- Add-ons Manager: show version number
- Toolbar buttons appearance known from 'Classic Toolbar Buttons'/'NoiaButtons' add-ons
-- classic appearance for menubar, tabs toolbar and main toolbars
-- custom border roundness for buttons on menubar, tabs toolbar and main toolbars
-- custom minimum height and width for buttons on menubar and main toolbars
-- custom icons: Thunderbird 1-3, macOS, dark, bright, Noia large/medium/small/tiny
-- icons: reduce icon size on hover
- Scrollbar settings
-- hide scrollbars / scrollbar buttons
-- custom size
-- custom opacity
-- background color/gradient
-- thumb color/gradient/roundness/border
-- button color/gradient/roundness
Compatibility
- compatible to Lightning
- compatible to Windows, Linux, macOS
- compatible to light and dark lw-themes (aka Personas)
- not compatible to complete themes
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CustomizeMyBird 2.0+ offers Thunderbird features from
- NewScrollbar add-on (present in CMB v1.2) (current version on AMO won't be updated for Tb59+)
- Classic Toolbar Buttons add-on (current version on AMO won't be updated for Tb59+)
- NoiaButtons add-on (current version on AMO won't be updated for Tb59+)
- Add-ons Manager - Version Number add-on (current version on AMO may still work, but won't be updated for Tb59+)
FAQ/Help
How to get application button to windows top left position?
- move menu button to tabs toolbar (customizing mode)
- go to CMBs options page
- hit option "Tabs and tab toolbar buttons: switch positions"
- hit option "Main appmenu button: alternative appearance"