WM_WINDOWPOSCHANGING Message Handler for Electron Application, which is always fixed on the floor.

electron-prevent-zorder-change.js

// Node.js & Electron reference : https://stackoverflow.com/a/58473299
// C++ reference : https://stackoverflow.com/a/65052538
// Environment:
// - Windows 10
// - Nodejs v14.17.6
// Dependencies:
// - electron@14.0.1
// - ref-napi@3.0.3
// - ref-struct-di@1.1.1
// - win-setwindowpos@2.1.0

/* // example in Electron main process.
const { 
  SetWindowPos,
  HWND_BOTTOM,
  SWP_SHOWWINDOW,
} = require('win-setwindowpos');

preventZOrderChange(win);
SetWindowPos(
  win.getNativeWindowHandle(),
  HWND_BOTTOM,
  0,
  700,
  800,
  600,
  SWP_SHOWWINDOW
);
*/

const ref = require('ref-napi');
const StructType = require('ref-struct-di')(ref);
const { 
  SetWindowPos,
  HWND_BOTTOM,
  SWP_NOACTIVATE,
  SWP_NOSIZE,
  SWP_NOMOVE,
  SWP_NOZORDER,
  SWP_NOSENDCHANGING,
} = require('win-setwindowpos');

const WINDOWPOS = StructType({
  hwnd: ref.types.int32,
  hwndInsertAfter: ref.types.int32,
  x: ref.types.int32,
  y: ref.types.int32,
  cx: ref.types.int32,
  cy: ref.types.int32,
  flags: ref.types.uint32,
});

const WM_WINDOWPOSCHANGING = 0x0046;

const preventZOrderChange = win => {
  win.hookWindowMessage(WM_WINDOWPOSCHANGING, (wParam, lParam)=> {
    const buf = Buffer.alloc(8);
    buf.type = ref.refType(WINDOWPOS);
    lParam.copy(buf);
    
    const actualStructDataBuffer = buf.deref();
    const windowPos = actualStructDataBuffer.deref();
    
    const newFlags = windowPos.flags | SWP_NOZORDER | SWP_NOMOVE | SWP_NOSIZE;
    actualStructDataBuffer.writeUInt32LE(newFlags, 6);
    actualStructDataBuffer.writeUInt32LE(HWND_BOTTOM, 1);
  });
};

module.exports = {
  WINDOWPOS,
  WM_WINDOWPOSCHANGING,
  preventZOrderChange,
};

Hey @lowfront, thank you for creating this gist. Could you please provide a more thorough sample code? I was not able to send the window to bottom using the example you provided here

EDIT:

So, I played with your code a bit, and found out that the example you provided works pretty well if you call preventZOrderChange after SetWindowPos. I am using Electron v16.