Spin the event loop to process the paste operation completely.

bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Combo.java

@@ -494,7 +494,12 @@ Point computeNativeSize (long h, int wHint, int hHint, boolean changed) {
  * <p>
  * The current selection is copied to the clipboard.
  * </p>
- *
+ * <p>
+ * <strong>Note:</strong> Copy data to the Clipboard may be asynchronous. This
+ * means that the new clipboard content may not be immediately available right
+ * after calling this method. To ensure the update is visible, use
+ * {@link Display#asyncExec(Runnable)} before accessing the clipboard data.
+ * </p>
  * @exception SWTException <ul>
  *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
  *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
@@ -1955,7 +1960,12 @@ long paintSurface () {
  * The selected text is deleted from the widget
  * and new text inserted from the clipboard.
  * </p>
- *
+ * <p>
+ * <strong>Note:</strong> Pasting data to controls may occurs asynchronously. The widget
+ * text may not reflect the updated value immediately after calling this method.
+ * The new text will appear once pending events are processed in the event loop.
+ * Use {@link Display#asyncExec(Runnable)} before accessing <code>getText()</code>.
+ * </p>
  * @exception SWTException <ul>
  *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
  *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>

tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_widgets_Combo.java

@@ -34,6 +34,7 @@
 import org.eclipse.swt.graphics.Point;
 import org.eclipse.swt.graphics.Rectangle;
 import org.eclipse.swt.widgets.Combo;
+import org.eclipse.swt.widgets.Display;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -236,6 +237,11 @@ public void test_copy() {
 	combo.copy();
 	combo.setSelection(new Point(0,0));
 	combo.paste();
+	// Spin the event loop to let GTK process the clipboard + entry update
+	Display display = combo.getDisplay();
+	while (display.readAndDispatch()) {
+	    // loop until no more events
+	}
 	assertEquals("23123456", combo.getText());
 }
 
@@ -501,6 +507,11 @@ public void test_paste() {
 	combo.cut();
 	assertEquals("1456", combo.getText());
 	combo.paste();
+	// Spin the event loop to let GTK process the clipboard + entry update
+	Display display = combo.getDisplay();
+	while (display.readAndDispatch()) {
+	    // loop until no more events
+	}
 	assertEquals("123456", combo.getText());
 }