Most of the instruction text explains how to build SciLexer.dll with and without boost, but I’ve never actually needed to do that. Instead, just put a recent copy of SciLexer.dll into the correct folder and build Notepad++ by itself.
Strictly speaking, this is not the right way to do it, but it has worked well enough for me that I have never noticed any missing functionality or other issues.
Although the official build instructions refer to VS2013, I was unable to build the solution using Visual Studio Community Edition 2013, which should be similar. However, it built perfectly the first time without any trouble using Visual Studio Community Edition 2015, so that’s what I recommend here.
Notepad++ comes in both portable and installer versions, but I prefer to use the installer because it automatically adds an Edit with Notepad++ option to the right-click file context menu. However, either version will work. After building notepad++.exe from source, just overwrite whichever version has been installed with the new executable.
Many useful plugins, such as Python Script, are not available in x64 versions, so it makes sense to build the x86 version instead.
Here are the steps to build from source and replace an existing installation:
Download the newest Notepad++ Installer 32-bit x86 file and install it to the default location C:\Program Files (x86)\Notepad++
Download or clone the Notepad++ source code and extract it to C:\work\npp
Download and install Microsoft Visual Studio Community Edition 2015.
Run Visual Studio and open the solution file C:\work\npp\PowerEditor\visual.net\notepadPlus.vcxproj.
Set the build target to create either a debug build or a release build:
select Unicode Debug and x86 to create a debug build
select Unicode Release and x86 to create a release build
Press F7 to build the solution, which will create notepad++.exe inside one of these build output folders:
C:\work\npp\PowerEditor\visual.net\Unicode Debug (for a debug build)
C:\work\npp\PowerEditor\bin (for a release build)
Copy the file SciLexer.dll from C:\Program Files (x86)\Notepad++ into the same build output folder as notepad++.exe in step 6.
Close any currently running instances of Notepad++.
Press F5 in Visual Studio to run the project and make sure Notepad++ starts and runs.
Copy the newly created version of notepad++.exe from one of the build output folders into C:\Program Files (x86)\Notepad++ to overwrite the previously installed version.
Run C:\Program Files (x86)\Notepad++\notepad++.exe to make sure everything works as expected.