LineEdit bug when removing text with align=right/center

[issork]

Godot version:
3.1-stable

Issue description:
When removing text from a LineEdit that has its alignment set to "Center" or "Right" and contains more text than can be shown, the caret starts acting weird. This gif shows it:

As you can see, the text is not being aligned properly and too few characters are drawn. With alignment set to "Center", it behaves like alignment set to "Left", then suddenly jumps back to the correct alignment when only one character remains.

Steps to reproduce:
Delete text from a full LineEdit with "Align" set to "Center" or "Right" by pressing backspace.

Edit:
This is also happening with align set to "Center", the offset is wrong until theres only one remaining character.

[samH-FIT]

Would this issue be stemming from line_edit.cpp? Or would it be coming from a more general file, like text_edit.cpp?

[issork]

@samH-FIT This comes from LineEdit, TextEdit doesn't have alignment.

I'm assuming this is due to a wrong x offset in

godot/scene/gui/line_edit.cpp

Line 681 in 9b69171

x_ofs = MAX(style->get_margin(MARGIN_LEFT), int(size.width - style->get_margin(MARGIN_RIGHT) - (cached_text_width)));

Edit: Noticed centered alignment has similar issues, the text isn't aligned properly until theres only 1 remaining character.

[KoBeWi]

I discovered that the bug comes from window_pos. It's not updated properly for non-left aligns.

[issork]

This isn't completetly fixed yet, as seen in the video below.
The order of the columns is in text alignment order, so the right column has align=right on it for example.

https://drive.google.com/open?id=1Lw4bwEbsztbKUkn5h8hkB3f8nM1QqkOR

As you can see, when removing text, there are still not enough characters drawn for center/right alignment. There are no more than 20 characters drawn at any point, even when it gets to the chars with a smaller width, which would allow for more characters drawn.

Edit: Added project that I used.
LineEditTest.zip

[KoBeWi]

I can confirm the above case in a920f97

[FeralBytes]

I still see this issue for right align and for place holder text centered in Godot 3.2.2-beta4 on Linux and Android.

[akien-mga]

The issue from #27421 (comment) seems still reproducible in 3.4 RC 1. CC @bruvzg @timothyqiu who have also been working on text controls and alignment.

[timothyqiu]

The left-aligned behavior also looks weird to me:

Normally, the line edit should be filled with text until there is not enough text:

I think this might be related to the wrong right/center align behavior.

[issork]

@timothyqiu I have a seperate issue for that #27420 ^^