Consider an 'advanced' mode with extra format bar icons

[aforcier]

In moving from the legacy to the visual editor, we dropped a few buttons (more, underline, and also strikethrough on phones in portrait mode). It might be a good idea to continue to offer those inside an 'advanced' format bar.

One idea from @maxme is to have the advanced format bar replace the keyboard when it's pulled up. We might replace the HTML mode button with an 'advanced format bar' button, and move the HTML mode button to the advanced format bar.

Of course this has the potential to introduce more WebView bugs (like blockquotes) and each has its own implementation issues (the more tag need to be represented in visual mode, for example).

[maxme]

• The "more" button is used by ~5% of users on Android (legacy editor) - very WP centric but that's not the only thing.
• Headings (h1/h2/h3/h4) seem like good candidates for an advanced format bar
• We could have a look at Calypso analytics on these buttons.

For comparison:

• Image button: 15%
• Bold: 5%
• More: 4.5%
• Italics: 4%
• Link: 4%
• Blockquote: 3%
• Underline: 2%
• Strikethrough: 1.75%

[rachelmcr]

A couple other buttons for consideration:

• Text alignment buttons (left, right, center, justify)
• Text color selection

These are both requested by users (alignment more often than color) and probably worth investigating if we are looking at Calypso usage analytics.

[maxme]

A "Paste without style" button could be useful when you need to paste formatted text (copied from a webpage for instance) to the editor.