There was an initiative by Niccolo Venerandi back in plasma 5 to unify tab styles in KDE (plasma, gear, etc). Ironically it resulted in the creation of even more tab styles. Currently there are at least:
- Tabs on the left side of DigiKam and bottom of Kate (no focus indicator line, surrounded by rectangle)
- Tabs in Dolphin (usual breeze/windows tab style with focus indicator lines on top)
- Tabs in the settings window of Dolphin (new immutable tab style with focus indicator lines on top)
- Tabs in the bottom bar of KClock (focus is indicated by accent color in background)
- Tabs in plasmoids (focus indicator on bottom)
- Tabs in qqc2-breeze style (similar to the new immutable tabs but qml)
- Custom tab widgets in amarok
Is there any plan to at least make these look similar?