Transparent window

Phoenix can make its own window (partially) see-through, so the desktop shows behind the game. It is what overlay and "desktop pet" mods need, and it is exposed to Lua, Python and Haxe.

Effect	What it does	Platforms
Color-key transparency	every pixel painted with the transparency color (RGB(1, 1, 1) by default) becomes see-through	Windows
Whole-window alpha	the window is drawn translucent (0.0 invisible → 1.0 opaque)	Windows, Linux, macOS
Click-through	the window ignores the mouse, clicks land on what is behind it	Windows

On HTML5, Flash/AIR, Android and iOS every call is a no-op that logs one line and returns false, so a mod can call them unconditionally.

Quick start (Lua)

function onCreatePost()
    if not isWindowTransparencySupported() then return end

    -- The pixels of this color disappear — the game background has to be it.
    setProperty('camGame.bgColor', '010101')
    setWindowTransparencyColor('010101')
    setWindowAlpha(0.9)
    setWindowTransparent(true)
end

function onDestroy()
    setWindowTransparent(false)   -- the window outlives the script: clean up
end

Quick start (Python)

def onCreatePost():
    if not isWindowTransparencySupported():
        return

    setProperty('camGame.bgColor', '010101')
    setWindowTransparencyColor('010101')
    setWindowAlpha(0.9)
    setWindowTransparent(True)


def onDestroy():
    setWindowTransparent(False)

Functions

Identical names in both languages — see Lua API reference and Python API reference:

setWindowTransparent(enable = true), getWindowTransparent(), setWindowAlpha(alpha), getWindowAlpha(), setWindowTransparencyColor(color), setWindowClickThrough(enable = true), isWindowClickThrough(), isWindowTransparencySupported(), applyWindowTransparency().

From Haxe:

import backend.TransparentWindow;

TransparentWindow.setColorKey(0xFF010101);
TransparentWindow.setAlpha(0.85);
TransparentWindow.setEnabled(true);
TransparentWindow.setClickThrough(true);

…or from HScript with addHaxeLibrary('TransparentWindow', 'backend').

Fullscreen

Transparency only makes sense on a windowed game, so the engine handles the window mode:

• enabling it while fullscreen leaves fullscreen first;
• entering fullscreen (F11, a script, …) suspends the effect, which comes back as soon as the game is windowed again — no setting is lost, and TransparentWindow.isActive reports what the window is doing right now.

Pitfalls

• Paint the color key. Nothing turns transparent until the background actually uses colorKey. Only that color is punched out: HUD, sprites and characters stay visible.
• Click-through needs a layered window (setWindowTransparent(true) or an alpha below 1), otherwise Windows ignores the flag — and it also means the player cannot click the game any more.
• Clean up in onDestroy. The window outlives the script.
• Nothing is persisted. There is no ClientPrefs entry on purpose: a mod that forgets to reset cannot leave the player with a permanently transparent game.

The full technical write-up — the Win32 implementation, the ported code and its credits, and the platform guard internals — lives in docs/TRANSPARENT_WINDOW.md.