Mercurial tries to pick which program to call to edit a commit message by trying the following (in order):
 1. {{{HGEDITOR}}} environment variable
 1. {{{editor}}} configuration option in {{{[ui]}}} section (in hgrc or passed with {{{--config ui.editor}}} command-line option).
 1. {{{VISUAL}}} environment variable
 1. {{{EDITOR}}} environment variable
 1. {{{vi}}}, if none of the above is set

On Windows, the installer places a configuration file inside {{{%programfiles%\Mercurial\hgrc.d\}}} that contains the editor settings ({{{notepad}}} by default).
Thus, if you want to override it, you either have to redefine the configuration option or use an {{{HGEDITOR}}} environment variable ({{{VISUAL}}} and {{{EDITOR}}} will be ignored).

== See also ==
 * [[HGEDITOR]]
 * [[hgeditor]]