Up/down arrow should read character by character in single line edit fields

[CyrilleB79]

Originally reported by @CyrilleB79 in #12632 (comment)

Steps to reproduce:

1. Focus a single line edit field, e.g.:
   • Open Windows Explorer and select a file
   • Press F2 to edit the file name
2. Press many times up and down arrows to navigate by character
3. Press many times ctrl+upaArrow and ctrl+downArrow to navigate by word
4. Press ctrl+home and ctrl+end to move to first and last char of the line

Note that in single line edit fields, moving to another line has no sense. Thus, MS has mapped vertical arrow movements to their corresponding movements with horizontal arrows, i.e. up/downArrow gestures move character by character as left/rightArrow gestures; and ctrl+up/downArrow gestures move word by word.

Actual behavior:

At each step, the whole line is read

Expected behavior:

2. Report current character rather than current line as Narrator does.
3. Report current word rather than current line.
4. Maybe report current character instead of current line to denote that there is no line change in this type of edit field? To be discussed.

System configuration

NVDA installed/portable/running from source:

Installed

NVDA version:

2021.2beta2 but probably any other one as well.

Windows version:

Windows 10 20H2 (64-bit) build 19042.1110

Name and version of other software in use when reproducing the issue:

N/A

Other information about your system:

N/A

Other questions

Does the issue still occur after restarting your computer?

Yes

Have you tried any other versions of NVDA? If so, please report their behaviors.

No but probably the same behaviour in other versions.

If add-ons are disabled, is your problem still occurring?

Yes

Does the issue still occur after you run the COM Registration Fixing Tool in NVDA's tools menu?

Not tested

Note: When resolving this issue, please test the STR in #12632. This issue is probably blocked by #12632.

[CyrilleB79]

@feerrenrut I can see that you have added the feature/windows-explorer label to this issue.
Note however that Windows Explorer is used as an example. But you may encounter this issue in any standard single line edit field.
For another unrelated example, just try in the filter field of the input gesture dialog of NVDA.

[LeonarddeR]

The fields you describe are edit controls (i.e. they have a window class of "Edit"). This looks like behavior that's only standard to these controls. I tried the subject fields of Mozilla Thunderbird and Outlook, and there this logic doesn't apply.

[CyrilleB79]

I have tested on my side on the subject field of Outlook which is Rich Edit. I can confirm @LeonarddeR's test, i.e. that vertical arrows do not act as horizontal ones in this field.
I have also tested in edit fields that are parts of a combo-box such as file name in a "Save as" dialog. They are also single line edit fields with a window class of Edit. However, since they are part of a combo-box, vertical arrows do not act as horizontal ones, since they are mapped for the combo-box usage, i.e. selection in the associated list.