## Feature Request: Improve Column Mode same as UltraEdit

[wanghlstar]

Description

Feature Request: Improve Column Mode same as UltraEdit

Current NotepadNext supports basic rectangular selection by Alt + drag mouse, but lacks many practical column‑editing features that UltraEdit(UE) provides.
For processing fixed‑width log / CSV / structured text, UE’s column‑mode is very convenient.

Describe the solution you'd like

P0 Must‑have：

1. Persistent toggle column‑block mode (shortcut like Alt+C in UE, menu entry in Edit menu, status‑bar indicator to show column‑mode is active)
2. Column insert sequential numbers (decimal/hex) in column selection
3. Column‑oriented operations: fill text into selected column block, delete whole‑column block
4. Column alignment: left‑align / right‑align / center for selected column block

P1 Nice‑to‑have:

1. Column sum for numeric values inside column selection
2. Column markers (vertical ruler line at specified column position)
3. Support find‑replace only within selected column block

Describe alternatives you've considered

Current Alt‑drag only gives temporary selection, no dedicated column operation menu. I have to switch back to UltraEdit for these tasks.

Additional context
UltraEdit column‑mode doc reference: https://wiki.ultraedit.com/Column_mode
My OS: macOS

[wanghlstar]

Use case:
I often process aligned multi-column text from database query results (3~5 or more columns), generate batch UPDATE / WHERE SQL statements.
Rows can be up to hundreds of thousands lines.
Current rectangle selection only supports typing directly after selection. This will create massive real-time multi-cursors and lag heavily on large files.

Required feature:
Add a Column Block Edit dialog, similar to Notepad-- / UltraEdit.
After selecting a rectangle range (via keyboard shift selection, no mouse drag), user can input text in dialog, then batch insert/replace into all selected lines in background, without rendering thousands of cursors.
Also support insert sequential numbers.