Mnemonics in menus are always displayed

[Chrriis]

With the system L&F (Windows 10), mnemonics are not displayed in menus unless I press the Alt key. With FlatLaf, mnemonics are always displayed.

I see that the FlatLaf code triggers repainting on the hierarchy when Alt is pressed or released, but this has no visual impact.

Unless I am mistaken, FlatMenuUI extends BasicMenuUI, and BasicMenuUI always paints the mnemonic. WindowsMenuItemUI (for system L&F) also extends BasicMenuItemUI but overrides paintText to have the mnemonic show/hide logic.

Please, let me know if I did something wrong 🙂

[DevCharly]

Mnemonic hiding was only implemented for labels, buttons and tabs.
Seems that I forgot the menus...

However, this is now implemented in master branch.

[Chrriis]

The fix works.

Minor details with regards to the Alt-key behavior (at least on Windows):

• If the window does not have a component with focus, then the fix does not work with FlatLaf.
• Pressing Alt on Windows L&F reveals the mnemonics but releasing it selects the first menu from the menu bar, which is not the case with FlatLaf.

Here is a test case:

	public static void main(String[] args) throws Exception {
//		UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
		UIManager.setLookAndFeel(new FlatLightLaf());
		JFrame frame = new JFrame();
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		JMenuBar menuBar = new JMenuBar();
		JMenu menu1 = new JMenu("Menu 1");
		menu1.setMnemonic('m');
		JMenuItem subMenu1_1 = new JMenuItem("Sub Menu 1.1");
		subMenu1_1.setMnemonic('s');
		menu1.add(subMenu1_1);
		menuBar.add(menu1);
		frame.setJMenuBar(menuBar);
//		frame.setContentPane(new JScrollPane(new JTextArea()));
		frame.setSize(400, 300);
		frame.setVisible(true);
	}

You can easily swap with the native L&F to see the difference (first comment), and you can easily add a focusable component (second comment).

[tanmatra]

Ok, now how I can disable this feature if I don't like it?

[DevCharly]

No problem. See "Show Mnemonics" section here: https://www.formdev.com/flatlaf/customizing/#show_mnemonics

[Chrriis]

I checked the latest changes and here are the current issues I found:

• if I Alt+Tab to switch to another window, and Alt+tab back, the mnemonics are showing while they should not.
• Pressing Alt on Windows L&F reveals the mnemonics but releasing it selects the first menu from the menu bar, which is not the case with FlatLaf. This is convenient for keyboard navigation when menus/submenus do not have mnemonics.

[DevCharly]

Chrriis wrote:

I don't know if this commit is responsible for a regression, but when I activate a parent menu by clicking, the mnemonics show!

No, commit 870d039 only hides the mnemonic when deactivating window (e.g. Alt+Tab to other window). This addresses the first point in #43 (comment)

Commit e3ed47b is responsible for showing mnemonics as soon as menu bar is active or a popup menu is visible.

What's wrong with this?
You can open a menu with the mouse, see the mnemonics and then execute an item with an mnemonic key. When you activate the menu with Alt+M then the mnemonics are also shown.

[Chrriis]

Well, mnemonics are noisy indications, so the original feature got tweaked to only reveal them when you press Alt. Activating a menu and having the UI blink everywhere with the mnemonics suddenly appearing is very odd.

[Chrriis]

As an additional comment, mnemonics are useful for people who want to use their keyboard to quickly jump. Basic users would simply use their mouse and they absolutely do not care about mnemonics and the graphical noise they add. Showing mnemonics on mouse actions is very odd.

[DevCharly]

Ok, thanks for your feedback. Sounds reasonable. I'll change it...

[Chrriis]

The behaviour of the mnemonics is much better with that last commit!

Now if I wanted to be picky, the only remaining issue I know is that pressing and releasing "Alt" on Windows should have the same effect than your F10 action (i.e. arm the first menu). Instead, it focuses on the top left icon of the window, and the proof is that if I press arrow down, it reveals the window icon top menu:

[DevCharly]

Now if I wanted to be picky, ...

Don't stop 😉 This brings FlatLaf forward. Details matter.

Activating menu with Alt key (on Windows) is now implemented in master branch.

[Chrriis]

Activating menu with Alt key (on Windows) is now implemented

Much better indeed.
I found that when you alt+tab to a different window and come back using alt+tab, Alt does not arm the menu the first time you press it. I personally do not care much about this issue though, and I find that other programs have similar problems (Eclipse activates the mnemonics for example).

[DevCharly]

Good catch 👍
Fixed in master

[smileatom]

good job guys.