Bug 143685

Created attachment 174022 [details]
A screencast of misaligned border after drag

When resizing Writer table cells using mouse, there is no snapping of dragged borders to the existing borders in the rows above/below. That makes it impossible to make a perfect alignment of the dragged border to existing borders in other rows, unless one later does a following drag of the almost-aligned border within a built-in allowance (20 twip = 0.35 mm), which would align all the almost-aligned borders, *but* would also resize the column - which is not always desirable.

Steps to reproduce:

1. Create a 3-column 2-row table.
2. Select A2:B2, and merge the cells.
3. In A2, split the cell vertically to 3 cells.
4. Zoom in to maximum to see the details.
5. Use mouse to drag a vertical border in row 2 to match a border of row 1.

See that usually the end result is not perfect; even though the following drag would treat those almost-aligned borders as one, it is still not perfect.

It will be usually even less perfect when not zooming in to the maximum. Users complain that they do not see when the border "snapped" to the adjacent borders' position [1] (which in fact does not happen at all, which is why they do not see it).

The proposal is to add the positions of existing borders in adjacent rows/columns to the snap positions of the drag operation. That would both create a useful visual feedback to users, and also allow for a perfect alignment when the snap occurs. It may be dynamically disabled e.g. when pressing a modifier key like Alt.

[1] https://forumooo.ru/index.php/topic,8735 (Russian)