UI Tooltips

[Marek Lewandowski]

As a part of #16373 and #14931 tasks we created a plugin that shows a tooltip for keyboard focus and mouse over.

We need to polish few things:

• UI, redesign it to look better, some ideas:
  • Positioning - tooltips should be cenetered to the button. Now they are just displayed underneath starting from left.
  • Triangle - Add an pointing triangle at the middle of it.
• Due to the fact that plugin was created to work with maximum portability it "knows" about possible integrations. We should reverse this, and say that tooltip will be applied for link elements with .cke_tooltip class, or anything like that.
  • It's OK for the plugin to directly replace toolbar buttons, as it's the only plugin required by keyboardtooltip.
• Plugin name, keyboardtooltip is no longer relevant as it's not only for keyboard but also for mouseover. Let's rename it simply to tooltip.
• There's a problem that the tooltip is visible right after opening the dialog (despite opening the dialog with mouse). The problem is that it overlays the content below the focused option. Here are the steps:
  1. Open ​smiley manual test.
  2. Click smiley button (this opens a dialog).

Expected: tooltip is not visible, as it hides "indecision" smiley.

The codebase is pushed to branch ​t/16706.