[Feature request] Search for Lines Not Matching

Is there an existing issue (open or closed) for this?

• I have searched the existing issues

Description of the Issue

Preparing a reg. exp. to find lines that do not include a string of characters (or strings) is not easy to do, so I thought why not add a tick box to invert the search. This could then be used for all of the search modes.

Describe the solution you'd like.

Add a tick box to invert the search (exclude the matching lines).

Debug Information

Notepad++ v8.9.6.4   (64-bit)
Build time: Jun  3 2026 - 23:47:49
Scintilla/Lexilla included: 5.6.2/5.4.9
Boost Regex included: 1_90
pugixml included: 1.15
nlohmann JSON included: 3.12.0
Path: C:\Program Files\Notepad++\notepad++.exe
Command Line: 
Admin mode: OFF
Local Conf mode: OFF
Cloud Config: OFF
WinGUp: present
disableNppAutoUpdate.xml: absent
Periodic Backup: ON
Placeholders: OFF
Scintilla Rendering Mode: SC_TECHNOLOGY_DEFAULT (0)
Multi-instance Mode: monoInst
asNotepad: OFF
File Status Auto-Detection: cdDisabled
Dark Mode: OFF
Display Info:
    primary monitor: 1920x1080, scaling 100%
    visible monitors count: 4
    installed Display Class adapters: 
        0000: Description - NVIDIA T1200 Laptop GPU
        0000: DriverVersion - 32.0.15.9647
        0001: Description - Intel(R) UHD Graphics
        0001: DriverVersion - 32.0.101.7026
        0002: Description - DisplayLink USB Device
        0002: DriverVersion - 9.3.3324.0
        0003: Description - DisplayLink USB Device
        0003: DriverVersion - 9.3.3324.0
    - warning, search has been limited to maximum number of adapter records: 4
OS Name: Windows 10 Pro (64-bit)
OS Version: 22H2
OS Build: 19045.6456
Current ANSI codepage: 1252
Plugins: 
    ComparePlus (2.2)
    mimeTools (3.1)
    NppConverter (4.7)
    NppExport (0.4)

Anything else?

No response

Start by locating the search dialog and the implementations for its existing search modes; the issue does not name specific files or tests. Trace how matching lines are selected, then verify that an inversion control excludes matching lines consistently across all search modes, with tests covering the new behavior.