[6.0] Fix deep submenu display

[bembelimen]

Summary of Changes

After https://github.com/joomla/joomla-cms/pull/45352 is merged, more issues with the menu can be fixed. This PR now fixes two issues:

• When there are more than two levels of menu items in the backend, the deeper levels has no correct padding
• When one of the sub-levels are opened there is a JS error and after refreshing the page the menu does not stay open

Testing Instructions

This is a bit tricky, as we have to kind of fake a deep hierarchy in the backend. So either create your own custom backend menu or we use a little trick to inject a deeper hierachy:

• Open administrator/modules/mod_menu/src/Menu/CssMenu.php
• Add the following code after line 423:

elseif ($item->element === 'com_contact' && isset($query['view']) && $query['view'] === 'contacts') {
    MenusHelper::loadPreset('content', false, $item);
}

This will load the content menu below the com_contact menu.

Actual result BEFORE applying this Pull Request

• When opening the deep hierarchy, a JS error is thrown:
• After refreshing the page, the selected active menu item is not opened
• Styling is not correct

Expected result AFTER applying this Pull Request

• No JS error
• Active menu item is visible
• Styling is correct

Link to documentations

Please select:

• [ ] Documentation link for docs.joomla.org:

• [x] No documentation changes for docs.joomla.org needed

• [ ] Pull Request link for manual.joomla.org:

• [x] No documentation changes for manual.joomla.org needed

[exlemor]

Hi @bembelimen, I have the BEFORE condition (including the JS console error and incorrect styling), after placing that code after line 423, but I have the standard design for that area and not what you show in your AFTER image - the good news there is NO JS console error which I have in the BEFORE situation once the PR is applied - so I think that I should show you:

[exlemor]

I have tested this item :white_check_mark: successfully on 88074e3cd1177ee215b520ff2df7051e1d81f517

I have tested this successfully. Thanks @bembelimen for the work!

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[brianteeman]

I have tested this item :white_check_mark: successfully on b7c7358cb088a6a7bb24fc5bdb8bcd6368da9b4b

replicated the problem with a custom admin menu and confirmed the fix

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[HLeithner]

RTC

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