TabbedPanel button text is rotated when 'tab_pos: "left_top"' is used

[GregDuckworthRenishaw]

Software Versions

• Python: 3.12.2
• OS: Windows 10 up to date
• Kivy: 2.3.0
• Kivy installation method: Pycharm via pip

Describe the bug

When a Tabbed Panel is defined in the kv file, with the option 'tab_pos: "left_top"', the resulting buttons are rotated 90 degrees such that the text runs from bottom to top on the screen. The rotation of the buttons is not readily changeable.

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Expected behavior
The button text should be able to be horizontal or vertical as needed.

A partial solution involving canvas.before: rotation results in a button that looks incorrect if the button is not square to begin with.

To Reproduce

from kivy.lang import Builder
from kivy.uix.tabbedpanel import TabbedPanel
from kivy.app import App

Builder.load_string('''
<WrongTab>:
    do_default_tab: False
    tab_pos: "left_top"
    tab_height: 150
    tab_width: 50
    TabbedPanelItem:
        text: "first heading"
''')


class WrongTab(TabbedPanel):
    pass


class TestApp(App):
    def build(self):
        return WrongTab()


if __name__ == "__main__":
    TestApp().run()

See below for current partial solution:

Code and Logs and screenshots

from kivy.lang import Builder
from kivy.uix.tabbedpanel import TabbedPanel
from kivy.app import App

Builder.load_string('''
<WrongTab>:
    do_default_tab: False
    tab_pos: "left_top"
    tab_height: 150
    tab_width: 50
    TabbedPanelItem:
        text: "first heading"
        canvas.before:
            PushMatrix
            Rotate:
                angle: -90
                origin: self.center
        canvas.after:
            PopMatrix
''')


class WrongTab(TabbedPanel):
    pass


class TestApp(App):
    def build(self):
        return WrongTab()


if __name__ == "__main__":
    TestApp().run()

Additional context
The background issue can be more clearly seen if the rotation angle is set to -45

[ElliotGarbus]

If you look at the tabbed_panel_showcase.py example, you can see how custom tabs can be rotated using a scatter.
https://github.com/kivy/kivy/blob/master/examples/widgets/tabbed_panel_showcase.py