I would like to know how to get a vertical file switcher on the left side i.e. in the left sidebar in Notepad++ 5.5?
I would like to have something like this as shown from the gedit editor?
You need to enable the 'Document Switcher' in the Peferences->General tab (it's a check box).
Once it's been enabled you should be able to just drag the window by the title bar onto the left side (it can be a bit fiddly for NP++ to detect the new location).
In Notepad++ v6.6.3, Settings > General > "List" Panel > check "Show under Document".
As of Notepad++ 7.5.1:
"Settings" menu > Preferences > General (left side of pane) > Document List Panel section > "Show" checkbox.
do you mean f ile explorer? there's a plugin you have to install first: plugins > plugin-manager > Show Plugin Manager, then search for 'Explorer' and install it. after restarting notepad++ go to plugins > explorer and check "explorer".
In addition to answer #2, you can use this plugin:
Plugins > Plugin Manager > Show Plugin Manager > select "Explorer" > Install.
The Explorer plugin will show your filesystem, rather than a list of open files (which is redundant because the open files are shown in the tabs at the top).
Based on Snowdude's answer, updated for v7.5.9 (64-bit)
Select on the menu:
Settings >> Preferences >> General >> Document List Panel >> Check "Show"