Implemented Shortcut to cycle open tabs

[shubham-shinde-442]

Resolves: #23702

Shortcut to cycle open tabs.

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[cbjeukendrup]

On macOS, it needs to be Meta instead of Ctrl.
For macOS, Qt namely automatically translates Ctrl to Cmd, and Cmd+Tab and Cmd+Shift+Tab are reserved system shortcuts.
For in-app tab switching, most macOS apps use the actual Ctrl key, and to get this with Qt, you need to write Meta.

[cbjeukendrup]

I would alter the navigateToSpecificTab method to take an int index rather than an action code.
Inside that method, you would need to do some sanity checks. (if (index < 0 || index >= m_notations.size()) { return; }
And here, you would need to write the index instead of the action code. Shouldn't be complicated though, for example these last two lines might become

Suggested change

	dispatcher()->reg(this, "eighth-tab", [this]() { navigateToSpecificTab("eighth-tab"); });
	dispatcher()->reg(this, "last-tab", [this]() { navigateToSpecificTab("last-tab"); });
	dispatcher()->reg(this, "eighth-tab", [this]() { navigateToSpecificTab(7); });
	dispatcher()->reg(this, "last-tab", [this]() { navigateToSpecificTab(m_notations.size() - 1); });

[shubham-shinde-442]

Updated.

[shoogle]

See #23702 (comment):

• Ctrl+Tab can cycle tabs but only while the score has focus.
• Ctrl+number can't be used for tabs, but Shift+Tab followed by a number or letter can be used.
  • Feel free to implement that in this PR or leave it out if you prefer.
  • If implemented, ideally it should be done in a general way that works for all UI lists, not just the tab bar.
• Tab key should visit every control.
  • That's a separate issue for a separate PR.
  • Please don't try to implement it until I've written a proper specification for it

[cbjeukendrup]

• Shift+Tab followed by a number or letter

• This would be a "key sequence", and weren't those banned in MS4 because they "were too much of a complication"?
• Shift+Tab is already in use as the 'opposite' of tab, i.e. move to previous control, isn't it?

[shoogle]

It's not a key sequence.

When you press Shift+Tab from the score it puts focus on the tab bar:

Now the program is in a different "context" and we can listen for a different set of shortcuts.

For example, press 'B' and it should focus the Bb Clarinet tab.

Quickly press 'A' (or just press 'B' again) and it should put focus on the Bassoon tab.

Press Space or Enter to load this tab (possibly press Tab) and then we're back in the Score context again.

(This score is the Wind Quartet template from the New Score dialog.)

[cbjeukendrup]

Ah, I see, so you mean like #16508. That should probably be implemented just in QML, bypassing the keyboard shortcuts system, so this shouldn't be affected by contexts. But it might be better to save that for a different PR.

[shubham-shinde-442]

Should this be implemented for all QML dropdowns, menus, lists, and treeviews, or just for tab bar? I'm happy to work on it but would appreciate some guidance on implementation.

[shoogle]

@shubham-shinde-442, it should be implemented for all of them except menus for the time being because it will interfere with Alt+letter mnemonics, so we need to decide what to do about that. (One option is to force people to keep holding the Alt key if they want to use mnemonics, but that might be unpopular. In Microsoft apps you can release Alt before you use a sequence of letters to navigate through a menu: Alt, F (File), S to save).

It should also be implemented for controls within a navigation panel, such as button in a toolbar. If you're in the note input toolbar and you press 'Q' it should focus the "Quarter note" button.

If there's an opportunity to share code rather than copy-pasting then it should be taken. If not then it can be split across several PRs, one for tab bars, one for dropdowns, one for lists, etc.

I've updated the description in #16508 with more details. See PR #5829 for a previous implementation in MuseScore 3.

I'm on vacation for the next 3 weeks so my capacity to help is limited, but I'm happy to test PR builds.