5 files changed, 45 insertions, 2 deletions

diff --git a/doc/ScintillaDoc.html b/doc/ScintillaDoc.html
index fdb12bc92..36868b308 100644
--- a/doc/ScintillaDoc.html
+++ b/doc/ScintillaDoc.html
@@ -192,7 +192,8 @@ SCI_SELECTALL
 SCI_GOTOLINE(int line)
 SCI_GOTOPOS(int position)
 SCI_GETCURLINE(int textlen, char *text)
-SCI_SETCARETPOLICY(int policy)
+SCI_SETCARETPOLICY(int policy, int slop)
+SCI_SETVISIBLEPOLICY(int policy, int slop)
 SCI_LINESONSCREEN
 SCI_SELECTIONISRECTANGLE
 SCI_SETHSCROLLBAR(bool visible)
@@ -213,7 +214,10 @@ SCI_GETHSCROLLBAR
     <p>
       SCI_SETCARETPOLICY can be set to a combination of the flags CARET_SLOP, 
       CARET_CENTER, and CARET_STRICT to change the automatic vertical positioning of the view
-      when ensuring a position is visible.
+      when ensuring a position is visible. SCI_SETVISIBLEPOLICY is a similar function that 
+      determines how the vertical positioning is determined when SCI_ENSUREVISIBLE is
+      called. It takes VISIBLE_SLOP, VISIBLE_CENTER, and VISIBLE_STRICT flags 
+      for the policy parameter.
     </p>
     <h3>
        Searching
diff --git a/include/Scintilla.h b/include/Scintilla.h
index da41bb6bf..099f2e3b7 100644
--- a/include/Scintilla.h
+++ b/include/Scintilla.h
@@ -382,6 +382,9 @@ typedef long (*SciFnDirect)(long ptr, unsigned int iMessage, unsigned long wPara
 #define SCI_WORDPARTLEFTEXTEND 2391
 #define SCI_WORDPARTRIGHT 2392
 #define SCI_WORDPARTRIGHTEXTEND 2393
+#define VISIBLE_SLOP 0x01
+#define VISIBLE_STRICT 0x04
+#define SCI_SETVISIBLEPOLICY 2394
 #define SCI_GRABFOCUS 2400
 #define SCI_STARTRECORD 3001
 #define SCI_STOPRECORD 3002
diff --git a/include/Scintilla.iface b/include/Scintilla.iface
index f5ea2f965..d1107388f 100644
--- a/include/Scintilla.iface
+++ b/include/Scintilla.iface
@@ -1030,6 +1030,13 @@ fun void WordPartRight=2392(,)
 # Move to the next change in capitalistion extending selection to new caret position.
 fun void WordPartRightExtend=2393(,)
 
+# Constants for use with SetVisiblePolicy
+val VISIBLE_SLOP=0x01
+#val VISIBLE_CENTER=0x02
+val VISIBLE_STRICT=0x04
+# Set the way the display area is determined when a particular line is to be moved to.
+fun void SetVisiblePolicy=2394(int visiblePolicy, int visibleSlop)
+
 # Set the focus to this Scintilla widget.
 # GTK+ Specific
 fun void GrabFocus=2400(,)
diff --git a/src/Editor.cxx b/src/Editor.cxx
index 6c7bda2b2..85958be8f 100644
--- a/src/Editor.cxx
+++ b/src/Editor.cxx
@@ -75,6 +75,9 @@ Editor::Editor() {
 	caretPolicy = CARET_SLOP;
 	caretSlop = 0;
 
+	visiblePolicy = VISIBLE_SLOP;
+	visibleSlop = 0;
+	
 	searchAnchor = 0;
 
 	ucWheelScrollLines = 0;
@@ -3148,6 +3151,24 @@ void Editor::EnsureLineVisible(int line) {
 		SetScrollBars();
 		Redraw();
 	}
+	if (visiblePolicy & VISIBLE_SLOP) {
+		if ((topLine > line) || ((visiblePolicy & VISIBLE_STRICT) && (topLine + visibleSlop > line))) {
+			SetTopLine(Platform::Clamp(line - visibleSlop, 0, MaxScrollPos()));
+			SetVerticalScrollPos();
+			Redraw();
+		} else if ((line > topLine + LinesOnScreen() - 1) ||
+		           ((visiblePolicy & VISIBLE_STRICT) && (line > topLine + LinesOnScreen() - 1 - visibleSlop))) {
+			SetTopLine(Platform::Clamp(line - LinesOnScreen() + 1 + visibleSlop, 0, MaxScrollPos()));
+			SetVerticalScrollPos();
+			Redraw();
+		}
+	} else {
+		if ((topLine > line) || (line > topLine + LinesOnScreen() - 1) || (visiblePolicy & VISIBLE_STRICT)) {
+			SetTopLine(Platform::Clamp(line - LinesOnScreen() / 2 + 1, 0, MaxScrollPos()));
+			SetVerticalScrollPos();
+			Redraw();
+		}
+	}
 }
 
 static bool ValidMargin(unsigned long wParam) {
@@ -4180,6 +4201,11 @@ long Editor::WndProc(unsigned int iMessage, unsigned long wParam, long lParam) {
 		caretSlop = lParam;
 		break;
 
+	case SCI_SETVISIBLEPOLICY:
+		visiblePolicy = wParam;
+		visibleSlop = lParam;
+		break;
+	
 	case SCI_LINESONSCREEN:
 		return LinesOnScreen();
 
diff --git a/src/Editor.h b/src/Editor.h
index 1bcac1665..52b3d7037 100644
--- a/src/Editor.h
+++ b/src/Editor.h
@@ -134,6 +134,9 @@ protected:	// ScintillaBase subclass needs access to much of Editor
 	int caretPolicy;
 	int caretSlop;
 
+	int visiblePolicy;
+	int visibleSlop;
+	
 	int searchAnchor;
 
 	int displayPopupMenu;