Hello everyone,
sorry I am very busy from my practical training as kitchen helper or cooker at restaurant / hospital. But I have 5 times of accidents.

My finger is not much cutting. Thanks for worrying me! I am shy to show because my finger in left middle finger
I am working at XLibSharp ( Wrapper for X11 ) on Ubuntu 18.04 and I have created simple window with button clicking.
It is really easy like Flash's Sprite
example:
Instance of Sprite = 1 = flash player or flash application. But XLib/X11 works also instance of window like sprite.
For XLib/X11 is very close to same to Flash Sprite Api
But I need create display, screen_number and window than I create any components.
XCreateSimpleWindow or XCreateWindow are very different levelly.
Example:
...
private IntPtr window, button;
...
window = XCreateSimpleWindow(....);
button = XCreateSimpleWindow(display, window, ...);
...
XMapWindow(display, window);
XMapWindow(display, button);
...
while(true)
{
// KeyPress for destroying window with break; It means Close window
...
// ButtonPress for clicking event with writing console or making new rectangle or widget of X11
...
}
...
XCloseDisplay(display);
I will release soon - I hope I can work sure 100 % with XLib/X11 wrapper for C#. But Steffen Ploetz's X11 libraries are very horrible because X11 libraries with shit enumerators. like TInt, TUlong or TPixel etc.. I really don't understand. I want use default types of mscorlib.dll ( using System; )
That is why I write clean library XLibSharp ( for only Linux, FreeBSD with only 64Bit - but I won't support for Windows - I know you want use with Cygwin's X11 - But I don't care with Cygwin. ) Please respect me! - I will try to create Half-life with XLib/X11 - Wait why it is easy? Because Half-Life has GUI like Steam GUI dialogues/windows. XLib/X11 has support also Vulkan too.
Sorry for longer busy because I have tried to resolve with GtkSharp3 and SDL2 = bad news if I add button than GtkSharp 3 application will crash. That is why I am trying to resolve as successful library for Linux and FreeBSD.
I hope you understand my English.
Best kind regards!