There's a distinction to make between rendered and visible rows, and we
were using the former as if it was the latter. In particular, if a tile
is visible, all its rows get rendered on screen, even though they might
not necessarily be visible by the user.
Also, remove specs testing RTL behavior. They don’t work as of today,
and I think we need a better approach to handle them, that doesn’t
solely rely on the DOM, but actually takes into account that e.g. (0, 0)
is the rightmost character on a right-to-left string.
Atom currently sets the `value` of the input on every `textInput` event, in an effort to appropriately handle changes made via the OSX diacritic menu (for accents, umlauts, etc).
The drawback of this is approach is that updating the value of the input will trigger layout and a subsequent layer tree update.
To resolve this, here is my proposal:
- Track a flag for `keypress` events. When the diacritic menu is used, there are two `textInput` events, with no `keypress` in between. Therefore, when no `keypress` has occurred just prior to a `textInput`, the editor model can select the previous character to be replaced by the new accented character.
- Track a flag for `compositionstart` events. When a user is in IME mode, the diacritic menu cannot be used, so the editor can skip the backward selection.
Test Plan:
Tested in a plaintext file.
- Type Latin characters, verify proper character insertion.
- Press and hold <kbd>a</kbd>. Diacritic menu appears. Select an option using the keyboard or mouse. Verify that the `a` is replaced by an accented `a`, with no extra characters.
- Type test strings in Katakana, 2-Set Korean, Telex (Vietnamese), Simplified Pinyin. Verify that characters are inserted correctly while composing, and after committing strings.
Instead, determine the need for a DOM update in the component before
measuring with the lines yardstick, and break `updateSync` into two
explicit pre- and post-measurement phases.
* Remove scrollRow and scrollColumn properties from the presenter
* Assign presenter's scrollTop and scrollLeft based on model's first visible
screen row and column, once the presenter has the required measurements.
