feat(ime): minimal IME support for the text_box widget

[kenz-gelsoft]

Fix the cosmic-edit specific part of pop-os/cosmic-epoch#2174.

The input method support in iced 14.0 requires text widgets to implement some logic to support input method input.

This PR includes this for the cosmic-edit specific text widgets in text_box.rs.

2026-03-24.23-54-27.mp4

FYI, my old PR of backporting the IME feature may be a good reference to add IME support for an existing custom text widget. See text_editor.rs:

• https://github.com/pop-os/iced/pull/255/changes#diff-f50c40e421b597328bff5e029fc5734fe37f7a9b084ba39699a95cac1ab107b7

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For text components other than text_box, the following PRs will add IME support:

• feat(text_input): Implement minimal IME support for COSMIC specific text widgets libcosmic#1182
• Bug fix for the find and replace feature:
  • fix(text_input): Fix focus detecting in IME logic libcosmic#1222

(I will force-push this branch to update my fork to rebase to newer upstream rev)

---

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[kenz-gelsoft]

I have a trivial fix not pushed.

[kenz-gelsoft]

Hi, is this waiting for QA?

My understanding is your QA will ensure my change doesn't break existing use-cases (mainly System76 hardware customers' non-IME use-cases).

Any input will help?

[jklgrasso]

Checklist:

Basic operations

• Type three lines of text (no trailing newline).
• Copy the last two lines.
• Paste at the end of the third line (file should now have four lines).
• Ctrl-Z to undo the paste.
  • Selecting text without using 'ctrl' causes undo to remove more than expected. Not a regression. Issue #564 created to address
• Press Enter to add a trailing newline.
• Paste again (file should now have five lines).
• Ctrl-Z to undo the paste.
• Ctrl-Shift-Z to redo the paste.
• Save the file.
• Ctrl-F and search for something that has a match.
• Press Esc twice to exit the Find dialog.
• Press Ctrl-X to cut the selected search result.
• Paste the cut text on a new line (file should now have six lines).
• Re-save the file.
• Narrow the window until the lines start wrapping (make a line longer if necessary to observe line wrapping).
• Turn word wrapping off.
• Scroll right to the end of the document, then left to the beginning again.
• Click and drag to select some text past the horizontal edge of the window.
• Close the file, open COSMIC Edit again, and open the file via the recents list.
  • Does not work. Not a regression
• Close the file again, open COSMIC Edit again, and open the file via the Open dialog.
• Turn word wrapping back on.

Settings

• Open View -> Settings.
• All Appearance settings work.
• Vim bindings work.

Projects & Git Management

• Clone the cosmic-edit Git repo and open its directory as a project.
• Edit -> Find in project... works.
• Make a change in a file.
• File -> Git management shows the change and staging it works.
• Make another change while Git management's open; it updates to show the new change.