From a360eeb6d300a1f61186744463c731f20b14c55c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=90=D0=BB=D0=B5=D0=BA=D1=81=D0=B0=D0=BD=D0=B4=D1=8A?=
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 <akurtakov@gmail.com>
Date: Thu, 7 May 2026 20:10:46 +0300
Subject: [PATCH] Fix PaintListener for GTK3 Table and Tree widgets
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GTK3 emits two draw-related signals:

* EXPOSE_EVENT_INVERSE (after=false) → before GTK draws items
* EXPOSE_EVENT (after=true) → after GTK draws items

SWT historically dispatched SWT.Paint during EXPOSE_EVENT_INVERSE.

For widgets like Table and Tree, GTK draws all rows/cells after this
point.
Result: anything drawn in a PaintListener was immediately overwritten.
---
 .../gtk/org/eclipse/swt/widgets/Table.java    | 41 ++++++++++++++++++-
 .../gtk/org/eclipse/swt/widgets/Tree.java     | 41 ++++++++++++++++++-
 2 files changed, 80 insertions(+), 2 deletions(-)

diff --git a/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Table.java b/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Table.java
index 2a39de05837..a72fb2f3a97 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Table.java	
+++ b/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Table.java	
@@ -2310,7 +2310,12 @@ long gtk_draw (long widget, long cairo) {
 		return 0;
 	}
 	drawInheritedBackground (cairo);
-	return super.gtk_draw (widget, cairo);
+	if (GTK.GTK4) {
+		return super.gtk_draw (widget, cairo);
+	} else {
+		// On GTK3 super.gtk_draw will be lost by items drawing thus handle explicitly in windowProc.
+		return 0;
+	}
 }
 
 @Override
@@ -4116,6 +4121,13 @@ long windowProc (long handle, long arg0, long user_data) {
 				}
 				propagateDraw(handle, arg0);
 			}
+			/*
+			 * Ensure the paint listener's drawing appears on top of items rather than being
+			 * overwritten by them.
+			 */
+			if (!GTK.GTK4) {
+				gtk3_paintEvent(arg0);
+			}
 			break;
 		}
 		case EXPOSE_EVENT_INVERSE: {
@@ -4194,6 +4206,33 @@ void checkSetDataInProcessBeforeRemoval(int start, int end) {
 	}
 }
 
+/**
+ * Fire the paint event explicitly, so the paint listener's drawing is not lost.
+ */
+private void gtk3_paintEvent(long cairo) {
+	if ((state & OBSCURED) != 0) return;
+	if (drawRegion) {
+		cairoClipRegion(cairo);
+	}
+	if (!hooksPaint()) return;
+	GdkRectangle rect = new GdkRectangle();
+	GDK.gdk_cairo_get_clip_rectangle(cairo, rect);
+	Event event = new Event();
+	event.count = 1;
+	Rectangle eventBounds = new Rectangle(rect.x, rect.y, rect.width, rect.height);
+	if ((style & SWT.MIRRORED) != 0) eventBounds.x = getClientWidth() - eventBounds.width - eventBounds.x;
+	event.setBounds(eventBounds);
+	GCData data = new GCData();
+	if (drawRegion) data.regionSet = eventRegion;
+	data.cairo = cairo;
+	GC gc = event.gc = GC.gtk_new(this, data);
+	gc.setClipping(eventBounds.x, eventBounds.y, eventBounds.width, eventBounds.height);
+	drawWidget(gc);
+	sendEvent(SWT.Paint, event);
+	gc.dispose();
+	event.gc = null;
+}
+
 @Override
 public void dispose() {
 	super.dispose();
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Tree.java b/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Tree.java
index c24b767bef7..aa25c3203c7 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Tree.java	
+++ b/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Tree.java	
@@ -2480,7 +2480,12 @@ long gtk_draw (long widget, long cairo) {
 		return 0;
 	}
 	drawInheritedBackground	(cairo);
-	return super.gtk_draw (widget, cairo);
+	if (GTK.GTK4) {
+		return super.gtk_draw (widget, cairo);
+	} else {
+		// On GTK3 super.gtk_draw will be lost by items drawing thus handle explicitly in windowProc.
+		return 0;
+	}
 }
 
 @Override
@@ -4192,6 +4197,13 @@ long windowProc (long handle, long arg0, long user_data) {
 				}
 				propagateDraw(handle, arg0);
 			}
+			/*
+			 * Ensure the paint listener's drawing appears on top of items rather than being
+			 * overwritten by them.
+			 */
+			if (!GTK.GTK4) {
+				gtk3_paintEvent(arg0);
+			}
 			break;
 		}
 		case EXPOSE_EVENT_INVERSE: {
@@ -4267,6 +4279,33 @@ void checkSetDataInProcessBeforeRemoval() {
 	}
 }
 
+/**
+ * Fire the paint event explicitly, so the paint listener's drawing is not lost.
+ */
+private void gtk3_paintEvent(long cairo) {
+	if ((state & OBSCURED) != 0) return;
+	if (drawRegion) {
+		cairoClipRegion(cairo);
+	}
+	if (!hooksPaint()) return;
+	GdkRectangle rect = new GdkRectangle();
+	GDK.gdk_cairo_get_clip_rectangle(cairo, rect);
+	Event event = new Event();
+	event.count = 1;
+	Rectangle eventBounds = new Rectangle(rect.x, rect.y, rect.width, rect.height);
+	if ((style & SWT.MIRRORED) != 0) eventBounds.x = getClientWidth() - eventBounds.width - eventBounds.x;
+	event.setBounds(eventBounds);
+	GCData data = new GCData();
+	if (drawRegion) data.regionSet = eventRegion;
+	data.cairo = cairo;
+	GC gc = event.gc = GC.gtk_new(this, data);
+	gc.setClipping(eventBounds.x, eventBounds.y, eventBounds.width, eventBounds.height);
+	drawWidget(gc);
+	sendEvent(SWT.Paint, event);
+	gc.dispose();
+	event.gc = null;
+}
+
 private void throwCannotRemoveItem(int i) {
 	String message = "Cannot remove item with index " + i + ".";
 	throw new SWTException(message);