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***

To reproduce, go to Settings and check "show history".

Bug1: 1+1=3
Type: 1 + MC 1 + 1 =
Where MC is the Memory Clear Button
The history will now display that 1+1=3

Bug2: 1+M=2 Where M=0
Type: 1 + 1 = 0 MS 1 + MS
Where MS is the Memory Store Button
The history will now display 1+M=2, while M=0

Bug3: Reading direction
Set the font size of the history to 11.
Type: 11 + 12 + 13 + 14 + 15 + 16 + 17 + 18 + 19 =
The history will now show:
 - With scrollbar: 11+12+13+14+15+161 newline 19=135+18+7+
 - Without scrollbar: 11+12+13+14+15+16+1 newline 19=135+18+7

Bug4: Font size 11 can be huge
Set the font size of the history to 11.
Make the window very wide.
The font in the history becomes huge.

UI improvement: history resize
If the window is very wide, both the buttons and the history QTextEdit become wider.
I'd like either the buttons to stay  the same width, and only the history to widen, OR the history QTextEdit to be manually resizable.
The formulae in the history can become quite wide, and it is best if the QTextEdit can be sized accordingly.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: NixOS
(available in About System)
KDE Plasma Version: 5.27.11
KDE Frameworks Version: 5.113.0
Qt Version: 5.15.12

ADDITIONAL INFORMATION
These bugs are very related, and therefore grouped together into one bug report.