Fix disabled wizard buttons appearing enabled in dark theme

In the dark theme, the CSS sets a foreground color on all Button elements,
which overrides the native OS disabled button rendering. This causes
disabled buttons (like 'Finish') to look identical to enabled ones.

Fix this by setting a 'disabled' CSS class on wizard buttons when they
are disabled. The dark theme CSS now includes a Button.disabled rule
with a dimmed foreground color. A reskin is triggered on state change
so the CSS engine re-applies styles without needing the global
dynamic CSS pseudo-class support (which is disabled for performance).

Author: vogella

bundles/org.eclipse.e4.ui.workbench3/plugin.xml

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<?eclipse version="3.4"?>
+<plugin>
+
+   <extension
+         id="product"
+         point="org.eclipse.core.runtime.products">
+      <product
+            name="e"
+            application="org.eclipse.ui.ide.workbench">
+         <property
+               name="appName"
+               value="e">
+         </property>
+      </product>
+   </extension>
+
+</plugin>

bundles/org.eclipse.jface/src/org/eclipse/jface/wizard/WizardDialog.java

@@ -973,7 +973,7 @@ private void restoreEnableState(Control control, Map<String,Object> saveState, S
 		if (control != null) {
 			Boolean b = (Boolean) saveState.get(key);
 			if (b != null) {
-				control.setEnabled(b.booleanValue());
+				setButtonEnabled(control, b.booleanValue());
 			}
 		}
 	}
@@ -1066,10 +1066,25 @@ public void run(boolean fork, boolean cancelable, IRunnableWithProgress runnable
 	private void saveEnableStateAndSet(Control control, Map<String, Object> saveState, String key, boolean enabled) {
 		if (control != null) {
 			saveState.put(key, control.getEnabled() ? Boolean.TRUE : Boolean.FALSE);
-			control.setEnabled(enabled);
+			setButtonEnabled(control, enabled);
 		}
 	}
 
+	/**
+	 * Sets the enabled state of a button and updates the CSS class name so that
+	 * the dark theme can style disabled buttons differently. The CSS class
+	 * "disabled" is set when the button is disabled, and cleared when enabled.
+	 * This triggers a reskin so that the CSS engine re-applies styles.
+	 *
+	 * @param control the button control
+	 * @param enabled whether the button should be enabled
+	 */
+	private static void setButtonEnabled(Control control, boolean enabled) {
+		control.setEnabled(enabled);
+		control.setData("org.eclipse.e4.ui.css.CssClassName", enabled ? null : "disabled"); //$NON-NLS-1$ //$NON-NLS-2$
+		control.reskin(SWT.NONE);
+	}
+
 	/**
 	 * Captures and returns the enabled/disabled state of the wizard dialog's
 	 * buttons and the tree of controls for the currently showing page. All
@@ -1332,13 +1347,13 @@ public void updateButtons() {
 		boolean canFinish = wizard.canFinish();
 		if (backButton != null) {
 			boolean backEnabled = currentPage != null && currentPage.getPreviousPage() != null;
-			backButton.setEnabled(backEnabled);
+			setButtonEnabled(backButton, backEnabled);
 		}
 		if (nextButton != null) {
 			canFlipToNextPage = currentPage != null && currentPage.canFlipToNextPage();
-			nextButton.setEnabled(canFlipToNextPage);
+			setButtonEnabled(nextButton, canFlipToNextPage);
 		}
-		finishButton.setEnabled(canFinish);
+		setButtonEnabled(finishButton, canFinish);
 		// finish is default unless it is disabled and next is enabled
 		if (canFlipToNextPage && !canFinish) {
 			getShell().setDefaultButton(nextButton);

bundles/org.eclipse.ui.themes/css/dark/e4-dark_globalstyle.css

@@ -45,6 +45,11 @@ Group > StyledText {
     color:'#org-eclipse-ui-workbench-DARK_FOREGROUND'; 
 }
 
+/* Disabled buttons should appear dimmed to distinguish them from enabled buttons */
+Button.disabled {
+    color: #777777;
+}
+
 /* ############################## Toolbar ############################## */
 /* Ensure that the labels in the tabfolder gets updated
    See Bug 552780

product/.project

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>product</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+	</buildSpec>
+	<natures>
+	</natures>
+</projectDescription>

product/.settings/org.eclipse.core.resources.prefs

@@ -0,0 +1,2 @@
+eclipse.preferences.version=1
+encoding/<project>=UTF-8

product/eclipse.product

@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<?pde version="3.5"?>
+
+<product name="e" uid="eclipse" id="org.eclipse.e4.ui.workbench3.product" application="org.eclipse.ui.ide.workbench" version="1.0.0.qualifier" type="mixed" includeLaunchers="true" autoIncludeRequirements="true">
+
+   <configIni use="default">
+   </configIni>
+
+   <launcherArgs>
+      <vmArgsMac>-XstartOnFirstThread -Dorg.eclipse.swt.internal.carbon.smallFonts
+      </vmArgsMac>
+   </launcherArgs>
+
+   <plugins>
+   </plugins>
+
+   <features>
+      <feature id="org.eclipse.sdk" installMode="root"/>
+   </features>
+
+   <configurations>
+      <plugin id="org.eclipse.core.runtime" autoStart="true" startLevel="4" />
+      <plugin id="org.eclipse.equinox.common" autoStart="true" startLevel="2" />
+      <plugin id="org.eclipse.equinox.event" autoStart="true" startLevel="2" />
+      <plugin id="org.apache.felix.scr" autoStart="true" startLevel="2" />
+      <plugin id="org.eclipse.equinox.simpleconfigurator" autoStart="true" startLevel="1" />
+   </configurations>
+
+</product>