[Win32] Remove OS.IsAppThemed() — always true on Windows 10+

Windows Classic theme was removed in Windows 8. Since SWT targets
Windows 10 and later, OS.IsAppThemed() unconditionally returns true,
making every !OS.IsAppThemed() branch unreachable dead code and every
if (OS.IsAppThemed()) guard reducible to its body.

Removes all 70+ call sites across 21 widget files:
- Dead !OS.IsAppThemed() else-branches are deleted (Classic theme
  fallbacks for DrawFrameControl, DFCS_* drawing, TBSTYLE_TRANSPARENT
  clearing, RTL text-clipping space-padding, ILC_MASK flag, etc.)
- if (OS.IsAppThemed()) guards are unwrapped to unconditional code
  (Explorer theme setup in Tree/Table createHandle, themed checkbox
  image lists in Tree/Table, THEME_BACKGROUND checks, wmColorChild,
  WM_ERASEBKGND, WM_MOVE, wmNCPaint, widgetStyle bits, etc.)
- Ternary OS.IsAppThemed() ? x : y expressions replaced with x
  (Group offsetY adjustments, ToolBar widgetStyle TBSTYLE_TRANSPARENT)
- Stale TEMPORARY CODE commented-out blocks removed (CoolBar, TabFolder)
- Group.fixText(boolean enabled): enabled parameter removed as it became
  unused once the Classic-theme space-padding workaround was deleted
- OS.IsAppThemed() declaration removed from OS.java (and auto-generated
  os.c / os_stats.h updated accordingly)

The following OS.java declarations became unused as a result and are
also removed:
- OS.DrawFrameControl() and its eleven associated constants
  (DFCS_BUTTONCHECK, DFCS_CHECKED, DFCS_FLAT, DFCS_INACTIVE,
  DFCS_PUSHED, DFCS_SCROLLDOWN, DFCS_SCROLLLEFT, DFCS_SCROLLRIGHT,
  DFCS_SCROLLUP, DFC_BUTTON, DFC_SCROLL) — only used in the non-themed
  checkbox and arrow-button drawing fallbacks
- OS.ImageList_AddMasked() — only used in the non-themed
  setCheckboxImageList() path (replaced by ImageList_Add)
- OS.BS_BITMAP and OS.BS_ICON — only used in the non-themed
  Button.enableWidget() RTL clipping workaround

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: HeikoKlare

bundles/org.eclipse.swt/Eclipse SWT PI/win32/library/os.c

@@ -1421,21 +1421,6 @@ JNIEXPORT jboolean JNICALL OS_NATIVE(DrawFocusRect)
 }
 #endif
 
-#ifndef NO_DrawFrameControl
-JNIEXPORT jboolean JNICALL OS_NATIVE(DrawFrameControl)
-	(JNIEnv *env, jclass that, jlong arg0, jobject arg1, jint arg2, jint arg3)
-{
-	RECT _arg1, *lparg1=NULL;
-	jboolean rc = 0;
-	OS_NATIVE_ENTER(env, that, DrawFrameControl_FUNC);
-	if (arg1) if ((lparg1 = getRECTFields(env, arg1, &_arg1)) == NULL) goto fail;
-	rc = (jboolean)DrawFrameControl((HDC)arg0, lparg1, arg2, arg3);
-fail:
-	OS_NATIVE_EXIT(env, that, DrawFrameControl_FUNC);
-	return rc;
-}
-#endif
-
 #ifndef NO_DrawIconEx
 JNIEXPORT jboolean JNICALL OS_NATIVE(DrawIconEx)
 	(JNIEnv *env, jclass that, jlong arg0, jint arg1, jint arg2, jlong arg3, jint arg4, jint arg5, jint arg6, jlong arg7, jint arg8)
@@ -3880,18 +3865,6 @@ JNIEXPORT jint JNICALL OS_NATIVE(ImageList_1Add)
 }
 #endif
 
-#ifndef NO_ImageList_1AddMasked
-JNIEXPORT jint JNICALL OS_NATIVE(ImageList_1AddMasked)
-	(JNIEnv *env, jclass that, jlong arg0, jlong arg1, jint arg2)
-{
-	jint rc = 0;
-	OS_NATIVE_ENTER(env, that, ImageList_1AddMasked_FUNC);
-	rc = (jint)ImageList_AddMasked((HIMAGELIST)arg0, (HBITMAP)arg1, (COLORREF)arg2);
-	OS_NATIVE_EXIT(env, that, ImageList_1AddMasked_FUNC);
-	return rc;
-}
-#endif
-
 #ifndef NO_ImageList_1BeginDrag
 JNIEXPORT jboolean JNICALL OS_NATIVE(ImageList_1BeginDrag)
 	(JNIEnv *env, jclass that, jlong arg0, jint arg1, jint arg2, jint arg3)
@@ -4442,18 +4415,6 @@ JNIEXPORT jboolean JNICALL OS_NATIVE(InvalidateRgn)
 }
 #endif
 
-#ifndef NO_IsAppThemed
-JNIEXPORT jboolean JNICALL OS_NATIVE(IsAppThemed)
-	(JNIEnv *env, jclass that)
-{
-	jboolean rc = 0;
-	OS_NATIVE_ENTER(env, that, IsAppThemed_FUNC);
-	rc = (jboolean)IsAppThemed();
-	OS_NATIVE_EXIT(env, that, IsAppThemed_FUNC);
-	return rc;
-}
-#endif
-
 #ifndef NO_IsHungAppWindow
 JNIEXPORT jboolean JNICALL OS_NATIVE(IsHungAppWindow)
 	(JNIEnv *env, jclass that, jlong arg0)

bundles/org.eclipse.swt/Eclipse SWT PI/win32/library/os_stats.h

@@ -129,7 +129,6 @@ typedef enum {
 	DragQueryFile_FUNC,
 	DrawEdge_FUNC,
 	DrawFocusRect_FUNC,
-	DrawFrameControl_FUNC,
 	DrawIconEx_FUNC,
 	DrawMenuBar_FUNC,
 	DrawText_FUNC,
@@ -304,7 +303,6 @@ typedef enum {
 	INITCOMMONCONTROLSEX_1sizeof_FUNC,
 	INPUT_1sizeof_FUNC,
 	ImageList_1Add_FUNC,
-	ImageList_1AddMasked_FUNC,
 	ImageList_1BeginDrag_FUNC,
 	ImageList_1Create_FUNC,
 	ImageList_1Destroy_FUNC,
@@ -344,7 +342,6 @@ typedef enum {
 	IntersectRect_FUNC,
 	InvalidateRect_FUNC,
 	InvalidateRgn_FUNC,
-	IsAppThemed_FUNC,
 	IsDarkModeAvailable_FUNC,
 	IsHungAppWindow_FUNC,
 	IsIconic_FUNC,

bundles/org.eclipse.swt/Eclipse SWT PI/win32/org/eclipse/swt/internal/win32/OS.java

@@ -134,14 +134,12 @@ public class OS extends C {
 	public static final int BST_INDETERMINATE = 0x2;
 	public static final int BST_UNCHECKED = 0x0;
 	public static final int BS_3STATE = 0x5;
-	public static final int BS_BITMAP = 0x80;
 	public static final int BS_CENTER = 0x300;
 	public static final int BS_CHECKBOX = 0x2;
 	public static final int BS_COMMANDLINK =  0xe;
 	public static final int BS_DEFPUSHBUTTON = 0x1;
 	public static final int BS_FLAT = 0x8000;
 	public static final int BS_GROUPBOX = 0x7;
-	public static final int BS_ICON = 0x40;
 	public static final int BS_LEFT = 0x100;
 	public static final int BS_MULTILINE = 0x2000;
 	public static final int BS_NOTIFY = 0x4000;
@@ -309,17 +307,7 @@ public class OS extends C {
 	public static final int DCX_CACHE = 0x2;
 	public static final int DEFAULT_CHARSET = 0x1;
 	public static final int DEFAULT_GUI_FONT = 0x11;
-	public static final int DFCS_BUTTONCHECK = 0x0;
-	public static final int DFCS_CHECKED = 0x400;
-	public static final int DFCS_FLAT = 0x4000;
-	public static final int DFCS_INACTIVE = 0x100;
-	public static final int DFCS_PUSHED = 0x200;
-	public static final int DFCS_SCROLLDOWN = 0x1;
-	public static final int DFCS_SCROLLLEFT = 0x2;
-	public static final int DFCS_SCROLLRIGHT = 0x3;
-	public static final int DFCS_SCROLLUP = 0x0;
-	public static final int DFC_BUTTON = 0x4;
-	public static final int DFC_SCROLL = 0x3;
+
 	public static final int DIB_RGB_COLORS = 0x0;
 	public static final int DI_NORMAL = 0x3;
 	public static final int DI_NOMIRROR = 0x10;
@@ -2605,11 +2593,7 @@ public static int HRESULT_FROM_WIN32(int x) {
  * @param lpRect flags=no_out
  */
 public static final native boolean DrawFocusRect (long hDC, RECT lpRect);
-/**
- * @param hdc cast=(HDC)
- * @param lprc flags=no_out
- */
-public static final native boolean DrawFrameControl (long hdc, RECT lprc, int uType, int uState);
+
 /**
  * @param hdc cast=(HDC)
  * @param hIcon cast=(HICON)
@@ -3108,12 +3092,7 @@ public static int HRESULT_FROM_WIN32(int x) {
  * @param hbmMask cast=(HBITMAP)
  */
 public static final native int ImageList_Add (long himl, long hbmImage, long hbmMask);
-/**
- * @param himl cast=(HIMAGELIST)
- * @param hbmImage cast=(HBITMAP)
- * @param crMask cast=(COLORREF)
- */
-public static final native int ImageList_AddMasked (long himl, long hbmImage, int crMask);
+
 /** @param himl cast=(HIMAGELIST) */
 public static final native boolean ImageList_BeginDrag (long himl, int iTrack, int dxHotspot, int dyHotspot);
 public static final native long ImageList_Create (int cx, int cy, int flags, int cInitial, int cGrow);
@@ -3254,7 +3233,6 @@ public static int HRESULT_FROM_WIN32(int x) {
  * @param hRgn cast=(HRGN)
  */
 public static final native boolean InvalidateRgn (long hWnd, long hRgn, boolean bErase);
-public static final native boolean IsAppThemed ();
 /** @method flags=no_gen */
 public static final native boolean IsDarkModeAvailable();
 /** @param hWnd cast=(HWND) */

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Button.java

@@ -211,11 +211,6 @@ void _setText (String text) {
 	* is disabled, the first pixel of the text is clipped.  The fix
 	* is to append a space to the text.
 	*/
-	if ((style & SWT.RIGHT_TO_LEFT) != 0) {
-		if (!OS.IsAppThemed ()) {
-			text = OS.IsWindowEnabled (handle) ? text : text + " ";
-		}
-	}
 	TCHAR buffer = new TCHAR (getCodePage (), text, true);
 	OS.SetWindowText (handle, buffer);
 	if ((state & HAS_AUTO_DIRECTION) != 0) {
@@ -391,12 +386,6 @@ Point computeSizeInPixels (Point hintInPoints, int zoom, boolean changed) {
 						} else {
 							rect.right -= 6;
 						}
-						if (!OS.IsAppThemed ()) {
-							rect.right -= 2;
-							if (isRadioOrCheck()) {
-								rect.right -= 2;
-							}
-						}
 					}
 					OS.DrawText (hDC, buffer, buffer.length, rect, flags);
 					width += rect.right - rect.left;
@@ -436,37 +425,31 @@ void createHandle () {
 	super.createHandle ();
 	parent.state &= ~IGNORE_WM_CHANGEUISTATE;
 
-	if (OS.IsAppThemed ()) {
-		/* Set the theme background.
-		*
-		* NOTE: On Vista this causes problems when the tab
-		* key is pressed for push buttons so disable the
-		* theme background drawing for these widgets for
-		* now.
-		*/
-		if ((style & (SWT.PUSH | SWT.TOGGLE)) == 0) {
-			state |= THEME_BACKGROUND;
-		}
-
-		/*
-		* Bug in Windows.  For some reason, the HBRUSH that
-		* is returned from WM_CTRLCOLOR is misaligned when
-		* the button uses it to draw.  If the brush is a solid
-		* color, this does not matter.  However, if the brush
-		* contains an image, the image is misaligned.  The
-		* fix is to draw the background in WM_CTRLCOLOR.
-		*
-		* NOTE: For comctl32.dll 6.0 with themes disabled,
-		* drawing in WM_ERASEBKGND will draw on top of the
-		* text of the control.
-		*/
-		if ((style & SWT.RADIO) != 0) {
-			state |= DRAW_BACKGROUND;
-		}
+	/* Set the theme background.
+	*
+	* NOTE: On Vista this causes problems when the tab
+	* key is pressed for push buttons so disable the
+	* theme background drawing for these widgets for
+	* now.
+	*/
+	if ((style & (SWT.PUSH | SWT.TOGGLE)) == 0) {
+		state |= THEME_BACKGROUND;
+	}
 
-		useDarkModeExplorerTheme = display.useDarkModeExplorerTheme;
-		maybeEnableDarkSystemTheme();
+	/*
+	* Bug in Windows.  For some reason, the HBRUSH that
+	* is returned from WM_CTRLCOLOR is misaligned when
+	* the button uses it to draw.  If the brush is a solid
+	* color, this does not matter.  However, if the brush
+	* contains an image, the image is misaligned.  The
+	* fix is to draw the background in WM_CTRLCOLOR.
+	*/
+	if ((style & SWT.RADIO) != 0) {
+		state |= DRAW_BACKGROUND;
 	}
+
+	useDarkModeExplorerTheme = display.useDarkModeExplorerTheme;
+	maybeEnableDarkSystemTheme();
 }
 
 private boolean customBackgroundDrawing() {
@@ -498,22 +481,6 @@ int defaultForeground () {
 void enableWidget (boolean enabled) {
 	super.enableWidget (enabled);
 	/*
-	* Bug in Windows.  When a Button control is right-to-left and
-	* is disabled, the first pixel of the text is clipped.  The fix
-	* is to append a space to the text.
-	*/
-	if ((style & SWT.RIGHT_TO_LEFT) != 0) {
-		if (!OS.IsAppThemed ()) {
-			int bits = OS.GetWindowLong (handle, OS.GWL_STYLE);
-			boolean hasImage = (bits & (OS.BS_BITMAP | OS.BS_ICON)) != 0;
-			if (!hasImage) {
-				String string = enabled ? text : text + " ";
-				TCHAR buffer = new TCHAR (getCodePage (), string, true);
-				OS.SetWindowText (handle, buffer);
-			}
-		}
-	}
-	/*
 	* Bug in Windows.  When a button has the style BS_CHECKBOX
 	* or BS_RADIOBUTTON, is checked, and is displaying both an
 	* image and some text, when BCM_SETIMAGELIST is used to
@@ -1257,9 +1224,7 @@ LRESULT WM_UPDATEUISTATE (long wParam, long lParam) {
 		boolean redraw = findImageControl () != null;
 		if (!redraw) {
 			if ((state & THEME_BACKGROUND) != 0) {
-				if (OS.IsAppThemed ()) {
-					redraw = findThemeControl () != null;
-				}
+				redraw = findThemeControl () != null;
 			}
 			if (!redraw) redraw = findBackgroundControl () != null;
 		}
@@ -1311,12 +1276,8 @@ private int getCheckboxTextOffset(long hdc) {
 
 	SIZE size = new SIZE();
 
-	if (OS.IsAppThemed ()) {
-		OS.GetThemePartSize(display.hButtonTheme(nativeZoom), hdc, OS.BP_CHECKBOX, OS.CBS_UNCHECKEDNORMAL, null, OS.TS_TRUE, size);
-		result += size.cx;
-	} else {
-		result += DPIUtil.pointToPixel(13, nativeZoom);
-	}
+	OS.GetThemePartSize(display.hButtonTheme(nativeZoom), hdc, OS.BP_CHECKBOX, OS.CBS_UNCHECKEDNORMAL, null, OS.TS_TRUE, size);
+	result += size.cx;
 
 	// Windows uses half width of '0' as checkbox-to-text distance.
 	OS.GetTextExtentPoint32(hdc, STRING_WITH_ZERO_CHAR, 1, size);
@@ -1540,24 +1501,10 @@ LRESULT wmDrawChild (long wParam, long lParam) {
 	OS.MoveMemory (struct, lParam, DRAWITEMSTRUCT.sizeof);
 	RECT rect = new RECT ();
 	OS.SetRect (rect, struct.left, struct.top, struct.right, struct.bottom);
-	if (OS.IsAppThemed ()) {
-		boolean pressed = ((struct.itemState & OS.ODS_SELECTED) != 0);
-		boolean enabled = getEnabled ();
-		int iStateId = getThemeStateId(style, pressed, enabled);
-		OS.DrawThemeBackground (display.hScrollBarThemeAuto(nativeZoom), struct.hDC, OS.SBP_ARROWBTN, iStateId, rect, null);
-	} else {
-		int uState = OS.DFCS_SCROLLLEFT;
-		switch (style & (SWT.UP | SWT.DOWN | SWT.LEFT | SWT.RIGHT)) {
-			case SWT.UP: uState = OS.DFCS_SCROLLUP; break;
-			case SWT.DOWN: uState = OS.DFCS_SCROLLDOWN; break;
-			case SWT.LEFT: uState = OS.DFCS_SCROLLLEFT; break;
-			case SWT.RIGHT: uState = OS.DFCS_SCROLLRIGHT; break;
-		}
-		if (!getEnabled ()) uState |= OS.DFCS_INACTIVE;
-		if ((style & SWT.FLAT) == SWT.FLAT) uState |= OS.DFCS_FLAT;
-		if ((struct.itemState & OS.ODS_SELECTED) != 0) uState |= OS.DFCS_PUSHED;
-		OS.DrawFrameControl (struct.hDC, rect, OS.DFC_SCROLL, uState);
-	}
+	boolean pressed = ((struct.itemState & OS.ODS_SELECTED) != 0);
+	boolean enabled = getEnabled ();
+	int iStateId = getThemeStateId(style, pressed, enabled);
+	OS.DrawThemeBackground (display.hScrollBarThemeAuto(nativeZoom), struct.hDC, OS.SBP_ARROWBTN, iStateId, rect, null);
 	return null;
 }