Zira Editor is a lightweight PHP Editor for Linux with syntax highlighting and autocomplete.
If you're looking for Geany alternative for KDE, you should try Zira Editor.
It's written in QT and can be run in both KDE and Gnome (also tested in Android and Raspbian Buster with Raspberry PI 3 B+).

Main features:
- low memory usage
- fast parser
- syntax highlighting
      PHP
      JavaScript
      CSS
      HTML
- autocomplete 
      PHP built-in functions and classes
      project classes, functions, variables
      JS objects, variables
      CSS selectors, properties
      HTML tags
- unused variables check
- files browser
- file symbols navigator
- highlight matching 
      brackets
      tags
      php expression (endif; endforeach;)
- function arguments display
- class auto import
- bulk comment in/out
- project state saving on exit
- F1 Help (PHP manual download required)
      php function docs
      php class docs
      php class method docs
- php lint integration (syntax check)
- php code sniffer integration
- git integration
      status browser
      annotations display
- sass support
- quick access panel (search files + symbols)
- go to declaration
      functions
      classes
      class methods
- search in files
- spell checker plugin (Hunspell library should be installed)
- built-in colorpicker
- built-in light and dark themes
- custom themes support

Tested in:
      OpenSuSe Leap 15.0
      OpenSuSe Leap 15.1
      Raspbian Buster
      
Requirements:
      Qt 5.10+ (5.12.6 is recommended)
      Hunspell (optional)

Compiled binary (x86-64) can be found in bin (or bin/arm for ARM) folder.
      
Installation:
      - download and unpack bin folder from ZIP-archive**
      - run install.sh
      
Install in Raspbian:
      - install qt5-default
      - install hunspell
      - download and unpack ZIP-archive**
      - copy bin/arm to any folder
      - copy bin/themes, bin/zira.png, bin/desktop.txt, bin/install.sh to the same folder
      - run install.sh
      
** - you can also download archive with all necessary files from releases section

If Qt version in your Linux distribution is < 5.12, download archive with linked Qt from releases section.