From d95237cefbbdbe3aa0b7ce315f5998b7181dcbe0 Mon Sep 17 00:00:00 2001
From: Nuno Cruces <ncruces@gmail.com>
Date: Fri, 24 Jan 2020 13:59:03 +0000
Subject: [PATCH] Color dialog title (windows).

---
 color_windows.go |  8 ++++++++
 util_windows.go  | 18 ++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/color_windows.go b/color_windows.go
index dd26d78..e24336a 100644
--- a/color_windows.go
+++ b/color_windows.go
@@ -46,6 +46,14 @@ func selectColor(options ...Option) (color.Color, error) {
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()
 
+	if opts.title != "" {
+		hook, err := hookDialogTitle(opts.title)
+		if hook == 0 {
+			return nil, err
+		}
+		defer unhookWindowsHookEx.Call(hook)
+	}
+
 	n, _, _ := chooseColor.Call(uintptr(unsafe.Pointer(&args)))
 
 	// save custom colors back
diff --git a/util_windows.go b/util_windows.go
index d24d292..0a211b8 100644
--- a/util_windows.go
+++ b/util_windows.go
@@ -49,6 +49,24 @@ type _CWPRETSTRUCT struct {
 	Wnd     uintptr
 }
 
+func hookDialogTitle(title string) (hook uintptr, err error) {
+	tid, _, _ := getCurrentThreadId.Call()
+	hook, _, err = setWindowsHookEx.Call(12, // WH_CALLWNDPROCRET
+		syscall.NewCallback(func(code int, wparam uintptr, lparam *_CWPRETSTRUCT) uintptr {
+			if lparam.Message == 0x0110 { // WM_INITDIALOG
+				name := [7]uint16{}
+				getClassName.Call(lparam.Wnd, uintptr(unsafe.Pointer(&name)), uintptr(len(name)))
+				if syscall.UTF16ToString(name[:]) == "#32770" { // The class for a dialog box
+					ptr := syscall.StringToUTF16Ptr(title)
+					setWindowText.Call(lparam.Wnd, uintptr(unsafe.Pointer(ptr)))
+				}
+			}
+			next, _, _ := callNextHookEx.Call(hook, uintptr(code), wparam, uintptr(unsafe.Pointer(lparam)))
+			return next
+		}), 0, tid)
+	return
+}
+
 type _COMObject struct{}
 
 func (o *_COMObject) Call(trap uintptr, a ...uintptr) (r1, r2 uintptr, lastErr error) {