IDEs and code editors have a lot offer but sometimes we just need to fast edit code maybe in a system that we still haven't installed another editor.
gedit is the simplest form of netbook but now let's try to make it more developer friendly.
While you have opened a window of gedit, up on the left select Text Editor-> Preferences.
On tab View you may want to check all Display options. On tab Editor set 4 spaces for a tab and enable automatic indentation. On Font & Colors select Oblivion theme. On Plugins check the File Browser Panel.
Close the prefereces. Now our simple text editor must already look more code friendly.
On the up right of the window, there is a hamburger menu. Click on it and select View. Enable Side Panel and Highlight Mode for PHP.
When I want to focus on a subfolder of my projects I prefer use gedit because I can double click on folders and list only this specific folder.
Also checkout Text Editor-> Keyboard Shortcuts to see all you can do faster.