Windows messages, subclassing, owner-draw, DWM frame styling, and WinRT for AHK v2. Use when intercepting window messages, subclassing a control, applying a dark title bar / Mica / Acrylic / rounded corners, or calling a Windows Runtime (WinRT) API. TRIGGER when: user says "OnMessage", "SendMessage/PostMessage", "subclass", "WM_", "owner-draw", "dark title bar", "Mica/Acrylic", "rounded corners", "WinRT", "clipboard history". Examples: "intercept WM_NOTIFY", "dark title bar on my GUI", "Mica backdrop", "use a WinRT API"
Windows messages, subclassing, owner-draw, DWM frame styling, and WinRT for AHK v2. Use when intercepting window messages, subclassing a control, applying a dark title bar / Mica / Acrylic / rounded corners, or calling a Windows Runtime (WinRT) API. TRIGGER when: user says "OnMessage", "SendMessage/PostMessage", "subclass", "WM_", "owner-draw", "dark title bar", "Mica/Acrylic", "rounded corners", "WinRT", "clipboard history". Examples: "intercept WM_NOTIFY", "dark title bar on my GUI", "Mica backdrop", "use a WinRT API"
AHK v2 WinAPI, DWM & WinRT
Apply native calls to the window/message system and modern Windows APIs.
How to use
Load the full reference from Modules/Module_WinAPI.md — messages, subclassing, owner-draw, DWM, WinRT activation.
Intercept messages with OnMessage(num, cb); the callback is cb(wParam, lParam, msg, hwnd) — keep it short and re-entrancy-safe.
Subclass via comctl32\SetWindowSubclass + a CallbackCreate proc kept alive on a long-lived object; defer to DefSubclassProc.
Frame styling (dark title bar, Mica/Acrylic, rounded corners) is dwmapi\DwmSetWindowAttribute; full control theming is Lib/DarkModeModular.ahk.
Quick answers
Bind a handler:OnMessage(0x4E, this.OnNotify.Bind(this)) — never an unbound method.
Dark title bar:DwmSetWindowAttribute(hwnd, 20, …, 4) + SetWindowTheme(hwnd, "DarkMode_Explorer", 0).
WinRT: activate via combase\RoGetActivationFactory, call interfaces by vtable index with ComCall (0-2 IUnknown, 3-5 IInspectable).
For the DWM constants, subclass lifetime rules, and the WinRT clipboard-history example, read Modules/Module_WinAPI.md.
