LengthInBufferCells() is not adequate to estimate buffer cells actually used by a line #1223

Just raising a potential issue.

When LengthInBufferCells() is used to estimate the buffer cells that an entire line will consume, it can be inaccurate when a double-wide character lands with only 1 cell remaining at the edge of the buffer. Functions such as ConvertOffsetToPoint() and ConvertLineAndColumnToOffset() do account for this.

The most likely places this will cause a problem is in trying to calculate where on the screen needs to be cleared after rendering an edited line.