First issue:

Place your cursor to n-th column of the line.
Move your cursor to m-th (m ≠ n) column of the line using arrow keys (left or right).
Press Up arrow key: your cursor columns is still m-th.

Place your cursor to n-th column of the line.
Move your cursor to m-th (m ≠ n) column of the line using Control + arrow keys (left or right).
Press Up arrow key...

Expected: your cursor columns is still m-th (like without Control).

Actual: your cursor column is n-th.



Second issue (with a two lines, first is bigger):

Place your cursor to n-th column of the first line (n higher than second line size).
Move your cursor to m-th column (m higher than second line size too).
Press Down arrow key: you’re at the end of second line.
Press Up arrow key:
-if you had moved your cursor without Control key, you’re at m-th column.
-if you had moved your cursor using Control key, you’re at n-th column.