Chapter 1: Introduction to Xlib
Chapter 2: Display Functions
Chapter 3: Window Functions
Chapter 4: Window Information Functions
Chapter 5: Pixmap and Cursor Functions
Chapter 6: Color Management Functions
Chapter 7: Graphics Context Functions
Chapter 8: Graphics Functions
Chapter 9: Window and Session Manager Functions
Chapter 10: Events
Chapter 11: Event Handling Functions
Chapter 12: Input Device Functions
Chapter 14: Inter-Client Communication Functions
Chapter 15: Resource Manager Functions
Chapter 16: Application Utility Functions
Index of functions
https://en.wikibooks.org/wiki/X_Window_Programming/Xlib