diff --git a/scintilla/doc/ScintillaHistory.html b/scintilla/doc/ScintillaHistory.html
index ff81657b1..b25f65b63 100644
--- a/scintilla/doc/ScintillaHistory.html
+++ b/scintilla/doc/ScintillaHistory.html
@@ -556,6 +556,27 @@
         Icons</a> Copyright(C) 1998 by Dean S. Jones<br />
       </li>
     </ul>
+    <h3>
+       <a href="https://www.scintilla.org/scite421.zip">Release 4.2.1</a>
+    </h3>
+    <ul>
+	<li>
+	Released 5 July 2019.
+	</li>
+	<li>
+	SciTE enables use of SCI_ commands in user.context.menu.
+	</li>
+ 	<li>
+	On Win32, stop the IME candidate window moving unnecessarily and position it better.<br />
+	Stop candidate window overlapping composition text and taskbar.<br />
+	Position candidate window closer to composition text.<br />
+	Stop candidate window moving while typing.<br />
+	Align candidate window to target part of composition text.<br />
+	Stop Google IME on Windows 7 moving while typing.<br />
+	<a href="https://sourceforge.net/p/scintilla/bugs/2120/">Bug #2120</a>.
+	<a href="https://sourceforge.net/p/scintilla/feature-requests/1300/">Feature #1300</a>.
+	</li>
+    </ul>
     <h3>
        <a href="https://www.scintilla.org/scite420.zip">Release 4.2.0</a>
     </h3>
diff --git a/scintilla/win32/ScintillaWin.cxx b/scintilla/win32/ScintillaWin.cxx
index 12fd71731..1deb8ca06 100644
--- a/scintilla/win32/ScintillaWin.cxx
+++ b/scintilla/win32/ScintillaWin.cxx
@@ -1063,11 +1063,17 @@ void ScintillaWin::SetCandidateWindowPos() {
 	IMContext imc(MainHWND());
 	if (imc.hIMC) {
 		const Point pos = PointMainCaret();
-		CANDIDATEFORM CandForm;
+		const PRectangle rcClient = GetTextRectangle();
+		CANDIDATEFORM CandForm{};
 		CandForm.dwIndex = 0;
-		CandForm.dwStyle = CFS_CANDIDATEPOS;
+		CandForm.dwStyle = CFS_EXCLUDE;
 		CandForm.ptCurrentPos.x = static_cast<LONG>(pos.x);
-		CandForm.ptCurrentPos.y = static_cast<LONG>(pos.y + vs.lineHeight);
+		CandForm.ptCurrentPos.y = static_cast<int>(pos.y + std::max(4, vs.lineHeight/4));
+		// Exclude the area of the whole caret line
+		CandForm.rcArea.top = static_cast<int>(pos.y);
+		CandForm.rcArea.bottom = static_cast<int>(pos.y + vs.lineHeight);
+		CandForm.rcArea.left = static_cast<int>(rcClient.left);
+		CandForm.rcArea.right = static_cast<int>(rcClient.right);
 		::ImmSetCandidateWindow(imc.hIMC, &CandForm);
 	}
 }
@@ -1217,8 +1223,12 @@ sptr_t ScintillaWin::HandleCompositionInline(uptr_t, sptr_t lParam) {
 			return 0;
 		}
 
-		if (initialCompose)
+		if (initialCompose) {
 			ClearBeforeTentativeStart();
+		}
+
+		// Set candidate window left aligned to beginning of preedit string.
+		SetCandidateWindowPos();
 		pdoc->TentativeStart(); // TentativeActive from now on.
 
 		std::vector<int> imeIndicator = MapImeIndicators(imc.GetImeAttributes());
@@ -1242,6 +1252,11 @@ sptr_t ScintillaWin::HandleCompositionInline(uptr_t, sptr_t lParam) {
 
 		MoveImeCarets(-CurrentPosition() + imeCaretPosDoc);
 
+		if (std::find(imeIndicator.begin(), imeIndicator.end(), SC_INDICATOR_TARGET) != imeIndicator.end()) {
+			// set candidate window left aligned to beginning of target string.
+			SetCandidateWindowPos();
+		}
+
 		if (KoreanIME()) {
 			view.imeCaretBlockOverride = true;
 		}
@@ -1249,7 +1264,6 @@ sptr_t ScintillaWin::HandleCompositionInline(uptr_t, sptr_t lParam) {
 		AddWString(imc.GetCompositionString(GCS_RESULTSTR), CharacterSource::imeResult);
 	}
 	EnsureCaretVisible();
-	SetCandidateWindowPos();
 	ShowCaretAtCurrentPosition();
 	return 0;
 }
@@ -2032,6 +2046,11 @@ void ScintillaWin::NotifyCaretMove() noexcept {
 
 void ScintillaWin::UpdateSystemCaret() {
 	if (hasFocus) {
+		if (pdoc->TentativeActive()) {
+			// ongoing inline mode IME composition, don't inform IME of system caret position.
+			// fix candidate window for Google Japanese IME moved on typing on Win7.
+			return;
+		}
 		if (HasCaretSizeChanged()) {
 			DestroySystemCaret();
 			CreateSystemCaret();