This is the big one.
The progress bar buttons and progress bars haven't been properly updated yet, since I have no new information about those. Also, some things currently look kind of weird because they were designed for a different layout. For instance, the layer view slider has a black rails on a black background, since it was designed for being on the white background of the 3D view.
Contributes to issue CURA-4148.
They need to be able to have a different text colour depending on whether you're hovering, the category is expanded or not, etc.
Contributes to issue CURA-4148.
This makes it easier to read and to modify this functionality rather than a string of ternary operators. It's about to become more complicated too.
Contributes to issue CURA-4148.
The new dark design specifies a colour for the print monitor overlay that is darker than what would be attainable with the default 75% opacity. So I'm making it 100% opacity (but still with a fade, so we need the opacity) and let the theme specify what opacity it wants.
Contributes to issue CURA-4148.
Since the zero point is always in the centre, we can just re-use this loop to prevent code duplication and gain a minor speed increase.
Contributes to issue CURA-4150.
This definition was provided to me via e-mail. The initial data was badly formatted, so I corrected it and verified back with Michael Wildermuth that the new profile worked. Apparently it works, so thank you Michael.
```
cura.desktop: error: (will be fatal in the future): value "cura-icon.png" for key "Icon" in group "Desktop Entry" is an icon name with an extension, but there should be no extension as described in the Icon Theme Specification if the value is not an absolute path
```
__Solution:__ Remove `.png`. __PLEASE NOTE__ that for this to work, cura-icon.png must be located in one of the directories in which desktops search for icons, such as `/usr/share/icons/hicolor/128x128/apps/`. Please make sure it ends up there (also in the AppImage, too.)
```
cura.desktop: error: value "application/sla;application/vnd.ms-3mfdocument;application/prs.wavefront-obj;image/bmp;image/gif;image/jpeg;image/png" for string list key "MimeType" in group "Desktop Entry" does not have a semicolon (';') as trailing character
```
__Solution:__ Add `;`
Reference:
https://travis-ci.org/AppImage/AppImageHub/builds/266072586#L538-L539
CURA-4188
Custom FDM printers in 2.5 don't have multi-extrusion support but they
do since 2.6. Upgrading from 2.5 to 2.6 will not create the missing
extruder stacks for the old custom FDM printers, which causes a crash.
This fix makes sure that all custom FDM printers will have 8 extruder
stacks during the upgrade so that Cura can still start normally and
those printers will still be usable.
