From 073480a615d644f8c61e339a500243db00989a80 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stefan=20K=C3=BCng?= <unknown>
Date: Tue, 27 Sep 2016 10:03:48 +1000
Subject: On Win32, mouse wheel scrolling can be restricted to only occur when
 the mouse is within the window.

---
 doc/ScintillaDoc.html     | 11 +++++++++++
 doc/ScintillaHistory.html |  4 ++++
 include/Scintilla.h       |  2 ++
 include/Scintilla.iface   |  5 +++++
 src/Editor.cxx            |  8 ++++++++
 src/Editor.h              |  1 +
 win32/ScintillaWin.cxx    | 12 ++++++++++++
 7 files changed, 43 insertions(+)

diff --git a/doc/ScintillaDoc.html b/doc/ScintillaDoc.html
index 681970d93..b348a68b7 100644
--- a/doc/ScintillaDoc.html
+++ b/doc/ScintillaDoc.html
@@ -2231,6 +2231,8 @@ struct Sci_TextToFind {
     <h2 id="MouseCapture">Mouse capture</h2>
     <a class="message" href="#SCI_SETMOUSEDOWNCAPTURES">SCI_SETMOUSEDOWNCAPTURES(bool captures)</a><br />
      <a class="message" href="#SCI_GETMOUSEDOWNCAPTURES">SCI_GETMOUSEDOWNCAPTURES</a><br />
+     <a class="message" href="#SCI_SETMOUSEWHEELCAPTURES">SCI_SETMOUSEWHEELCAPTURES(bool captures)</a><br />
+     <a class="message" href="#SCI_GETMOUSEWHEELCAPTURES">SCI_GETMOUSEWHEELCAPTURES</a><br />
 
     <p><b id="SCI_SETMOUSEDOWNCAPTURES">SCI_SETMOUSEDOWNCAPTURES(bool captures)</b><br />
      <b id="SCI_GETMOUSEDOWNCAPTURES">SCI_GETMOUSEDOWNCAPTURES</b><br />
@@ -2238,6 +2240,15 @@ struct Sci_TextToFind {
     sent to Scintilla. This behaviour may be turned off with
     <code>SCI_SETMOUSEDOWNCAPTURES(0)</code>.</p>
 
+    <p><b id="SCI_SETMOUSEWHEELCAPTURES">SCI_SETMOUSEWHEELCAPTURES(bool captures)</b><br />
+     <b id="SCI_GETMOUSEWHEELCAPTURES">SCI_GETMOUSEWHEELCAPTURES</b><br />
+     On Windows, Scintilla captures all <code>WM_MOUSEWHEEL</code> messages if it has the
+     focus, even if the mouse pointer is nowhere near the Scintilla editor window. This
+     behavior can be changed with <code>SCI_SETMOUSEWHEELCAPTURES(0)</code> so that
+     Scintilla passes the <code>WM_MOUSEWHEEL</code> messages to its parent window.
+     Scintilla will still react to the mouse wheel if the mouse pointer is over
+     the editor window.</p>
+
     <h2 id="LineEndings">Line endings</h2>
 
     <p>Scintilla can handle the major line end conventions and, depending on settings and
diff --git a/doc/ScintillaHistory.html b/doc/ScintillaHistory.html
index 99ae922f1..a6079cfeb 100644
--- a/doc/ScintillaHistory.html
+++ b/doc/ScintillaHistory.html
@@ -530,6 +530,10 @@
 	EDGE_MULTILINE and SCI_MULTIEDGEADDLINE added to allow displaying multiple
 	vertical edges simultaneously.
 	<li>
+	<li>
+	On Win32, mouse wheel scrolling can be restricted to only occur when the mouse is
+	within the window.
+	<li>
 	The WordList class in lexlib used by lexers adds an InListAbridged method for
 	matching keywords that have particular prefixes and/or suffixes.
 	</li>
diff --git a/include/Scintilla.h b/include/Scintilla.h
index 0b5483043..2d6b06b22 100644
--- a/include/Scintilla.h
+++ b/include/Scintilla.h
@@ -682,6 +682,8 @@ typedef sptr_t (*SciFnDirect)(sptr_t ptr, unsigned int iMessage, uptr_t wParam,
 #define SCI_GETSTATUS 2383
 #define SCI_SETMOUSEDOWNCAPTURES 2384
 #define SCI_GETMOUSEDOWNCAPTURES 2385
+#define SCI_SETMOUSEWHEELCAPTURES 2696
+#define SCI_GETMOUSEWHEELCAPTURES 2697
 #define SC_CURSORNORMAL -1
 #define SC_CURSORARROW 2
 #define SC_CURSORWAIT 4
diff --git a/include/Scintilla.iface b/include/Scintilla.iface
index d52c229bf..bee9aeef8 100644
--- a/include/Scintilla.iface
+++ b/include/Scintilla.iface
@@ -1755,6 +1755,11 @@ set void SetMouseDownCaptures=2384(bool captures,)
 # Get whether mouse gets captured.
 get bool GetMouseDownCaptures=2385(,)
 
+# Set whether the mouse wheel can be active outside the window.
+set void SetMouseWheelCaptures=2696(bool captures,)
+# Get whether mouse wheel can be active outside the window.
+get bool GetMouseWheelCaptures=2697(,)
+
 enu CursorShape=SC_CURSOR
 val SC_CURSORNORMAL=-1
 val SC_CURSORARROW=2
diff --git a/src/Editor.cxx b/src/Editor.cxx
index beec634d3..ee4d3947f 100644
--- a/src/Editor.cxx
+++ b/src/Editor.cxx
@@ -112,6 +112,7 @@ Editor::Editor() {
 	hasFocus = false;
 	errorStatus = 0;
 	mouseDownCaptures = true;
+	mouseWheelCaptures = true;
 
 	lastClickTime = 0;
 	doubleClickCloseThreshold = Point(3, 3);
@@ -7594,6 +7595,13 @@ sptr_t Editor::WndProc(unsigned int iMessage, uptr_t wParam, sptr_t lParam) {
 	case SCI_GETMOUSEDOWNCAPTURES:
 		return mouseDownCaptures;
 
+	case SCI_SETMOUSEWHEELCAPTURES:
+		mouseWheelCaptures = wParam != 0;
+		break;
+
+	case SCI_GETMOUSEWHEELCAPTURES:
+		return mouseWheelCaptures;
+
 	case SCI_SETCURSOR:
 		cursorMode = static_cast<int>(wParam);
 		DisplayCursor(Window::cursorText);
diff --git a/src/Editor.h b/src/Editor.h
index 72d4719ed..ee56700dd 100644
--- a/src/Editor.h
+++ b/src/Editor.h
@@ -176,6 +176,7 @@ protected:	// ScintillaBase subclass needs access to much of Editor
 
 	bool hasFocus;
 	bool mouseDownCaptures;
+	bool mouseWheelCaptures;
 
 	int xCaretMargin;	///< Ensure this many pixels visible on both sides of caret
 	bool horizontalScrollBarVisible;
diff --git a/win32/ScintillaWin.cxx b/win32/ScintillaWin.cxx
index 10d119b5a..3de78d1d4 100644
--- a/win32/ScintillaWin.cxx
+++ b/win32/ScintillaWin.cxx
@@ -1272,6 +1272,18 @@ sptr_t ScintillaWin::WndProc(unsigned int iMessage, uptr_t wParam, sptr_t lParam
 			break;
 
 		case WM_MOUSEWHEEL:
+			if (!mouseWheelCaptures) {
+				// if the mouse wheel is not captured, test if the mouse
+				// pointer is over the editor window and if not, don't
+				// handle the message but pass it on.
+				RECT rc;
+				GetWindowRect(MainHWND(), &rc);
+				POINT pt;
+				pt.x = GET_X_LPARAM(lParam);
+				pt.y = GET_Y_LPARAM(lParam);
+				if (!PtInRect(&rc, pt))
+					return ::DefWindowProc(MainHWND(), iMessage, wParam, lParam);
+			}
 			// if autocomplete list active then send mousewheel message to it
 			if (ac.Active()) {
 				HWND hWnd = static_cast<HWND>(ac.lb->GetID());
-- 
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