UI scales when toggling theme

[yunkhngn]

I'm using Python and Tkinter for GUI. I've a function using switch and ttk for switching between light and dark mode:

def ThemeChanger():
    if screen.tk.call("ttk::style", "theme", "use") == "sun-valley-dark":
        # Set light theme
        screen.tk.call("set_theme", "light")
    else:
        # Set dark theme
        screen.tk.call("set_theme", "dark"

But when I clicked into the switch, all the UI automatically scales a litter bit:

It will scale larger if i use tabs or table in ttk Tkinter, and won't scale back when switch to light mode, it scales more and more when I clicked into theme switch button:

def change_theme():
    # NOTE: The theme's real name is sun-valley-<mode>
    if root.tk.call("ttk::style", "theme", "use") == "sun-valley-dark":
        # Set light theme
        root.tk.call("set_theme", "light")
    else:
        # Set dark theme
        root.tk.call("set_theme", "dark")

I don't know how to fix this. I would so appreciate if anyone can recommend me improving these. Thank you!

[rdbende]

Duplicate of #6
I just quickly done a diff light.tcl dark.tcl and I found nothing that might cause this issue. I remember I saw this issue with other ttk themes, but it's strange that it scales back when changing back to light theme.

[stojshic]

I'm not sure that this is the same problem as in #6. I have the same problem in my app. I use tabs for different parts of UI, and if I'm in empty tab, it only scales once and stays the same, doesn't go bigger or smaller, but if I'm in the tab that has treeview, it gets bigger every time I use sv_ttk.toggle_theme(), can't figure out why... It doesn't shrink when returning to white theme like in #6, it just expands the UI for a bit...

[rdbende]

Probably related to rdbende/Azure-ttk-theme#20

[rdbende]

From the README:

When you change the theme, and your app has a treeview, the window resizes. This is a quite strange bug that applies to other ttk themes too.

[rdbende]

Probably related to rdbende/Azure-ttk-theme#20

Not related to it. This is a bug in Tk itself. rdbende/Azure-ttk-theme#40

[rdbende]

Bug reported in Tk core: https://core.tcl-lang.org/tk/tktview?name=bc602049ab