From b9f7871e66900f60bbec4b203b36ea4122e108f0 Mon Sep 17 00:00:00 2001
From: Tobias Melcher <tobias.melcher@sap.com>
Date: Fri, 28 Nov 2025 13:43:17 +0100
Subject: [PATCH] Ignore blank color defaults in ColorsAndFontsPreferencePage

Fixes https://github.com/eclipse-platform/eclipse.platform.ui/issues/3559
---
 .../themes/ColorsAndFontsPreferencePage.java  |  6 ++++-
 .../ui/internal/themes/LightColorFactory.java | 22 ++++++++++++++-----
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/themes/ColorsAndFontsPreferencePage.java b/bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/themes/ColorsAndFontsPreferencePage.java
index 93dd53bf64b..ce48e843223 100644
--- a/bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/themes/ColorsAndFontsPreferencePage.java
+++ b/bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/themes/ColorsAndFontsPreferencePage.java
@@ -1352,12 +1352,16 @@ private RGB getColorTakingPreferenceDefaultValueIntoAccount(ColorDefinition defi
 			return valueFromExtension;
 		}
 		String storeDefault = store.getDefaultString(id);
-		if (storeDefault == null) {
+		if (storeDefault == null || storeDefault.isBlank()) {
 			return valueFromExtension;
 		}
 		try {
 			RGB defaultRGB = ColorUtil.getColorValue(storeDefault);
 			if (defaultRGB != null && !defaultRGB.equals(valueFromExtension)) {
+				if (getActiveTheme() != null
+						&& LightColorFactory.isColorDefinitionIdPartOfLightColorFactory(id)) {
+					return valueFromExtension;
+				}
 				return defaultRGB;
 			}
 		} catch (DataFormatException e) { // silently ignored
diff --git a/bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/themes/LightColorFactory.java b/bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/themes/LightColorFactory.java
index c739134ac76..4721dee731f 100644
--- a/bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/themes/LightColorFactory.java
+++ b/bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/themes/LightColorFactory.java
@@ -15,7 +15,6 @@
 package org.eclipse.ui.internal.themes;
 
 import java.util.Hashtable;
-
 import org.eclipse.core.runtime.IConfigurationElement;
 import org.eclipse.core.runtime.IExecutableExtension;
 import org.eclipse.swt.graphics.RGB;
@@ -31,6 +30,10 @@
  */
 public class LightColorFactory implements IColorFactory, IExecutableExtension {
 
+	private static final String ACTIVE_NOFOCUS_TAB_BG_START = "org.eclipse.ui.workbench.ACTIVE_NOFOCUS_TAB_BG_START"; //$NON-NLS-1$
+	private static final String ACTIVE_TAB_TEXT_COLOR = "org.eclipse.ui.workbench.ACTIVE_TAB_TEXT_COLOR"; //$NON-NLS-1$
+	private static final String ACTIVE_TAB_BG_END = "org.eclipse.ui.workbench.ACTIVE_TAB_BG_END"; //$NON-NLS-1$
+	private static final String ACTIVE_TAB_BG_START = "org.eclipse.ui.workbench.ACTIVE_TAB_BG_START"; //$NON-NLS-1$
 	protected static final RGB white = ColorUtil.getColorValue("COLOR_WHITE"); //$NON-NLS-1$
 	protected static final RGB black = ColorUtil.getColorValue("COLOR_BLACK"); //$NON-NLS-1$
 
@@ -157,23 +160,30 @@ private RGB getActiveNofocusStartColor() {
 		return ColorUtil.blend(white, base, 40);
 	}
 
+	static boolean isColorDefinitionIdPartOfLightColorFactory(String id) {
+		if (ACTIVE_TAB_BG_START.equals(id) || ACTIVE_TAB_BG_END.equals(id) || ACTIVE_TAB_TEXT_COLOR.equals(id)
+				|| ACTIVE_NOFOCUS_TAB_BG_START.equals(id)) {
+			return true;
+		}
+		return false;
+	}
+
 	@Override
 	public RGB createColor() {
 		// should have base, otherwise error in the xml
 		if (baseColorName == null || definitionId == null) {
 			return white;
 		}
-
-		if (definitionId.equals("org.eclipse.ui.workbench.ACTIVE_TAB_BG_START")) { //$NON-NLS-1$
+		if (definitionId.equals(ACTIVE_TAB_BG_START)) {
 			return getActiveFocusStartColor();
 		}
-		if (definitionId.equals("org.eclipse.ui.workbench.ACTIVE_TAB_BG_END")) { //$NON-NLS-1$
+		if (definitionId.equals(ACTIVE_TAB_BG_END)) {
 			return getActiveFocusEndColor();
 		}
-		if (definitionId.equals("org.eclipse.ui.workbench.ACTIVE_TAB_TEXT_COLOR")) { //$NON-NLS-1$
+		if (definitionId.equals(ACTIVE_TAB_TEXT_COLOR)) {
 			return getActiveFocusTextColor();
 		}
-		if (definitionId.equals("org.eclipse.ui.workbench.ACTIVE_NOFOCUS_TAB_BG_START")) { //$NON-NLS-1$
+		if (definitionId.equals(ACTIVE_NOFOCUS_TAB_BG_START)) {
 			return getActiveNofocusStartColor();
 		}