Compute foreground and background colors for both setEnabled and

setEditable

the foreground and background colors were computed only for setEnabled.
This has to be done for setEditable as
well to achieve consistency. This commit adds the same update to
setEditable function as well.
The background color and foreground color for the styled text when the
background is
not editable doesn't differentiate anything. This commit also adds a
different foreground and background color combination.This improves
visual differentiation in StyledText.

Fixes :#3132

Author: elsazac

bundles/org.eclipse.swt/Eclipse SWT Custom Widgets/common/org/eclipse/swt/custom/StyledText.java

@@ -8290,8 +8290,10 @@ public void setBackground(Color color) {
 	customBackground = color != null && !this.insideSetEnableCall && !backgroundDisabled;
 	background = color;
 	super.setBackground(color);
-	resetCache(0, content.getLineCount());
-	setCaretLocations();
+	if (content != null) {
+		resetCache(0, content.getLineCount());
+		setCaretLocations();
+	}
 	super.redraw();
 }
 /**
@@ -8772,6 +8774,40 @@ public void setDragDetect (boolean dragDetect) {
 	checkWidget ();
 	this.dragDetect = dragDetect;
 }
+
+/**
+ * Applies foreground and background colors based on the control's state.
+ * Custom foreground and background settings are preserved and not overridden.
+ *
+ * @param enabled  {@code true} if the control is enabled; {@code false} otherwise
+ * @param editable {@code true} if the control is editable; {@code false} otherwise
+ * @since 3.134
+ */
+protected void updateColors(boolean enabled, boolean editable) {
+	this.insideSetEnableCall = true;
+	Display display = getDisplay();
+	try {
+		if (enabled && editable) {
+			if (!customBackground)
+				setBackground(display.getSystemColor(SWT.COLOR_LIST_BACKGROUND));
+			if (!customForeground)
+				setForeground(display.getSystemColor(SWT.COLOR_LIST_FOREGROUND));
+		} else if (!enabled) {
+			if (!customBackground)
+				setBackground(display.getSystemColor(SWT.COLOR_TEXT_DISABLED_BACKGROUND));
+			if (!customForeground)
+				setForeground(display.getSystemColor(SWT.COLOR_WIDGET_DISABLED_FOREGROUND));
+		} else if (!editable) {
+			if (!customBackground)
+				setBackground(display.getSystemColor(SWT.COLOR_TITLE_INACTIVE_BACKGROUND));
+			if (!customForeground)
+				setForeground(display.getSystemColor(SWT.COLOR_GRAY));
+		}
+	} finally {
+		this.insideSetEnableCall = false;
+	}
+}
+
 /**
  * Sets whether the widget content can be edited.
  *
@@ -8785,28 +8821,13 @@ public void setDragDetect (boolean dragDetect) {
 public void setEditable(boolean editable) {
 	checkWidget();
 	this.editable = editable;
+	updateColors(this.enabled, this.editable);
 }
 @Override
 public void setEnabled(boolean enabled) {
 	super.setEnabled(enabled);
-	Display display = getDisplay();
 	this.enabled = enabled;
-	this.insideSetEnableCall = true;
-	try {
-		if (enabled && editable) {
-			if (!customBackground) setBackground(display.getSystemColor(SWT.COLOR_LIST_BACKGROUND));
-			if (!customForeground) setForeground(display.getSystemColor(SWT.COLOR_LIST_FOREGROUND));
-		} else if(!enabled) {
-			if (!customBackground) setBackground(display.getSystemColor(SWT.COLOR_TEXT_DISABLED_BACKGROUND));
-			if (!customForeground) setForeground(display.getSystemColor(SWT.COLOR_WIDGET_DISABLED_FOREGROUND));
-		} else if(!editable) {
-			if (!customBackground) setBackground(display.getSystemColor(SWT.COLOR_TEXT_DISABLED_BACKGROUND));
-			if (!customForeground) setForeground(display.getSystemColor(SWT.COLOR_LIST_FOREGROUND));
-		}
-	}
-	finally {
-		this.insideSetEnableCall = false;
-	}
+	updateColors(this.enabled, this.editable);
 }
 
 @Override
@@ -8885,8 +8906,10 @@ public void setForeground(Color color) {
 	customForeground = color != null && !this.insideSetEnableCall && !foregroundDisabled;
 	foreground = color;
 	super.setForeground(color);
-	resetCache(0, content.getLineCount());
-	setCaretLocations();
+	if (content != null) {
+		resetCache(0, content.getLineCount());
+		setCaretLocations();
+	}
 	super.redraw();
 }
 /**