[Bug] mlterm causes Zellij frame misalignment when printing Arabic characters

[MrNewbie72]

Summary:
When using mlterm to print Arabic characters inside Zellij multiplexer, the Zellij frame becomes misaligned or "off" after the Arabic text is printed.

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Steps to Reproduce:

1. Open Zellij multiplexer.
2. Launch mlterm inside the Zellij session.
3. Print Arabic text containing the combination of ا (Alef) and ل (Lam)
4. Observe that the frame of Zellij (especially the layout of windows and panes) becomes misaligned or "off" after the Arabic characters are printed.
5. Note: I also tried using different fonts in mlterm, but the issue persists regardless of the font selected.

Observe that the pipe symbol (|) shifts into the Arabic text, misaligning the layout and making the Zellij frame appear off.

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Expected Behavior:
The Arabic characters should be rendered correctly within the mlterm window inside Zellij, and the Zellij frame (layout and pane borders) should remain intact and not shift or misalign.

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Version Information:

• mlterm version: master build
• OS version: Debian 12

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Please let me know if any further details are needed or if I can assist with reproducing the issue.

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جزاكم الله خيراً

[arakiken]

Thank you for your report.

Terminal emulators and console applications assume that U+644 and U+627 occupy 2 columns.
Mlterm shows U+FEFB (arabic presentation form) which occupies 1 column for U+644 + U+627.
As a result, the misalignment occurs.
It is impossible to fix the misalignment unless terminal emulators and console applications
regard U+644 + U+627 as 1 column.

To avoid the misalignment, I added --adc option. (use_arabic_dynamic_comb)
If you change it dynamically, please look at the screenshot.
https://mlterm.sf.net/arabicshape.png