Disabling a selected tab in TabbedContent leaves it selected

[davep]

With #3145 in mind and this applied:

diff --git a/src/textual/widgets/_tabbed_content.py b/src/textual/widgets/_tabbed_content.py
index e3d8d20c2..99d12ba1b 100644
--- a/src/textual/widgets/_tabbed_content.py
+++ b/src/textual/widgets/_tabbed_content.py
@@ -381,7 +381,7 @@ class TabbedContent(Widget):
         event.stop()
         tab_id = event.tab.id
         try:
-            self.query_one(f"TabPane#{tab_id}").disabled = True
+            self.get_child_by_id(f"TabPane#{tab_id}").disabled = True
         except NoMatches:
             return
 
@@ -404,7 +404,7 @@ class TabbedContent(Widget):
             Tabs.TabError: If there are any issues with the request.
         """
 
-        self.query_one(Tabs).disable(tab_id)
+        self.get_child_by_type(Tabs).disable(tab_id)
 
     def enable_tab(self, tab_id: str) -> None:
         """Enables the tab with the given ID.
@@ -416,7 +416,7 @@ class TabbedContent(Widget):
             Tabs.TabError: If there are any issues with the request.
         """
 
-        self.query_one(Tabs).enable(tab_id)
+        self.get_child_by_type(Tabs).enable(tab_id)
 
     def hide_tab(self, tab_id: str) -> None:
         """Hides the tab with the given ID.
@@ -428,7 +428,7 @@ class TabbedContent(Widget):
             Tabs.TabError: If there are any issues with the request.
         """
 
-        self.query_one(Tabs).hide(tab_id)
+        self.get_child_by_type(Tabs).hide(tab_id)
 
     def show_tab(self, tab_id: str) -> None:
         """Shows the tab with the given ID.
@@ -440,4 +440,4 @@ class TabbedContent(Widget):
             Tabs.TabError: If there are any issues with the request.
         """
 
-        self.query_one(Tabs).show(tab_id)
+        self.get_child_by_type(Tabs).show(tab_id)

consider this code:

from textual.app import App, ComposeResult
from textual.widgets import TabbedContent, TabPane, Label

class TabsInTabsApp(App[None]):

    def compose(self) -> ComposeResult:
        with TabbedContent(id="top-level"):
            with TabPane("One", id="one"):
                yield Label("This is tab one level one")
            with TabPane("Two", id="two"):
                yield Label("This is tab two level one")
            with TabPane("Go Deeper", id="deeper"):
                with TabbedContent():
                    with TabPane("One", id="one"):
                        yield Label("This is tab one level one")
                    with TabPane("Two", id="two"):
                        yield Label("This is tab two level one")

    def on_mount(self) -> None:
        top_level_tabs = self.query_one("#top-level", TabbedContent)
        top_level_tabs.disable_tab("one")

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

On startup the disabled tab will still be selected. Perhaps when a tab is disabled the next eligible tab should be selected (much like I believe it does if you remove a tab?).

[rodrigogiraoserrao]

Disabled tabs can be selected if they're disabled after being selected, and that's by design.

Inside on_mount things have already been mounted and you just happened to disable a tab that was already selected.

When a tab is disabled do we want to move automatically to the next one, then?

[davep]

When a tab is disabled do we want to move automatically to the next one, then?

I sense it's something we should consider. IIRC don't we move focus of a widget when it is disabled? If so I feel we should attempt similar when it comes to tabs.

[rodrigogiraoserrao]

IIRC don't we move focus of a widget when it is disabled?

Yes

If so I feel we should attempt similar when it comes to tabs.

You may be right.
Who do we talk to? 😆

[davep]

I think we get to decide. :-)

[rodrigogiraoserrao]

I'm all up for being consistent with how focus works in other situations.
Then, disabling a tab should move the active tab just like hiding does?

[davep]

Then, disabling a tab should move the active tab just like hiding does?

I've not seen/tested hiding, but if it works as I'd expect then, yeah, I think that's likely what people would expect to happen (assuming disabled really is "can't be selected at all, no way, not at all").

[rodrigogiraoserrao]

You haven't seen hiding? That's because it's working correctly! 😆

assuming disabled really is "can't be selected at all, no way, not at all

That's it.

[davep]

You haven't seen hiding? That's because it's working correctly!

rimshot.gif

[rodrigogiraoserrao]

I think I'll go back on this.

There's precedent in other frameworks for a disabled tab that isn't automatically unselected, much like disabling a button wouldn't suddenly interrupt whatever actions were being carried out because the button was clicked previously.
Plus, in the edge case where all existing tabs are disabled, it looks very awkward if no pane is visible (even if disabled).

@davep do you think this is sensible at all or do you firmly believe we should deactivate a disabled tab?

[davep]

I've got no firm view either way really (I was just refreshing my memory on how VCL did/does it and it's anything goes really, if I'm reading it correctly). Personally I'd favour least astonishment within the context of how disabled works more generally in Textual.

[rodrigogiraoserrao]

I'm closing this as “wontfix” with the caveat that this was a close call and therefore the decision might be reversed in the future.

Arguments in favour of not deactivating the currently-active tab if it is disabled, in no particular order:

• an argument alluding to how focus goes out of a widget if it is disabled suggested we should activate another tab immediately, but focus doesn't cycle out of the currently-active tab, so there's really no expectation for the focus to automatically jump to another widget in another tab if the currently active tab is disabled;
• Qt behaves in this way; (win32 doesn't allow disabling tabs and I couldn't figure out what tkinter does from their docs)
• the edge case where we deactivate all tabs would look really odd because the tabbed content would be “empty”

[github-actions]

Don't forget to star the repository!

Follow @textualizeio for Textual updates.