fix: dont loose selection when opening&closing cluster list (#23869)

src/main/kotlin/com/redhat/devtools/gateway/view/ui/FilteringComboBox.kt

@@ -13,8 +13,6 @@
 
 import com.intellij.openapi.util.Key
 import java.awt.event.ActionListener
-import java.awt.event.FocusAdapter
-import java.awt.event.FocusEvent
 import java.awt.event.ItemEvent
 import java.awt.event.KeyAdapter
 import java.awt.event.KeyEvent
@@ -26,6 +24,7 @@
 object FilteringComboBox {
 
     private val popupOpened = PopupOpened()
+    private val popupSelection = PopupSelection()
 
     fun <T> create(
         toString: (T?) -> String = { it.toString() },
@@ -53,6 +52,7 @@
         toString: (T) -> String
     ): PopupMenuListener = object : PopupMenuListener {
         override fun popupMenuWillBecomeVisible(e: PopupMenuEvent?) {
+            popupSelection.backup(comboBox)
             val allItems = comboBox.filteringModel().getAllItems()
             val editorText = getEditorComponent(comboBox)?.text ?: ""
             val visible = if (popupOpened.isProgrammatic(comboBox)) {
@@ -65,8 +65,13 @@
             popupOpened.reset(comboBox)
         }
 
-        override fun popupMenuWillBecomeInvisible(e: PopupMenuEvent?) {}
-        override fun popupMenuCanceled(e: PopupMenuEvent?) {}
+        override fun popupMenuWillBecomeInvisible(e: PopupMenuEvent?) {
+            popupSelection.restore(comboBox)
+        }
+
+        override fun popupMenuCanceled(e: PopupMenuEvent?) {
+            popupSelection.restore(comboBox)
+        }
     }
 
     private fun <T> onListItemRendered(toString: (T) -> String): ListCellRenderer<T> =
@@ -121,15 +126,16 @@
     ) {
         popupOpened.setProgrammatic(true, comboBox)
         val editor = getEditorComponent(comboBox)
-        val selection = Selection(comboBox.editor.editorComponent as? JTextComponent).backup()
+        val JTextSelection = JTextSelection(comboBox.editor.editorComponent as? JTextComponent).backup()
 
         val currentTextInEditor = editor?.text ?: ""
         comboBox.filteringModel().showOnly(items)
 
         editor?.text = currentTextInEditor
 
         // Restore the selection after the model and text are set
-        selection.restore()
+        JTextSelection.restore()
+        popupSelection.backup(comboBox)
         comboBox.selectedIndex = -1 // prevent pre-selection
 
         if (items.isNotEmpty() && !comboBox.isPopupVisible) {
@@ -224,12 +230,12 @@
         }
     }
 
-    private class Selection(private val component: JTextComponent?) {
+    private class JTextSelection(private val component: JTextComponent?) {
 
         private var selectionStart = -1
         private var selectionEnd = -1
 
-        fun backup(): Selection {
+        fun backup(): JTextSelection {
             if (component == null) {
                 return this
             }
@@ -247,6 +253,26 @@
         }
     }
 
+    private class PopupSelection {
+
+        private val key = Key.create<Any?>("${FilteringComboBox.javaClass.name}Selection")
+
+        fun backup(comboBox: JComboBox<*>) {
+            if (comboBox.getClientProperty(key) == null) {
+                // only backup once (multiple selection changes happen in normal flow)
+                comboBox.putClientProperty(key, comboBox.selectedItem)
+            }
+        }
+
+        fun restore(comboBox: JComboBox<*>) {
+            val backedUp = comboBox.getClientProperty(key) ?: return
+            comboBox.putClientProperty(key, null)
+            if (comboBox.selectedIndex == -1) {
+                comboBox.selectedItem = backedUp
+            }
+        }
+    }
+
     private class PopupOpened {
 
         private val key = Key.create<Boolean>("isPopupProgrammatic")

src/test/kotlin/com/redhat/devtools/gateway/view/ui/FilteringComboBoxTest.kt

@@ -16,6 +16,7 @@ import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.BeforeEach
 import java.awt.event.KeyEvent
 import javax.swing.*
+import javax.swing.event.PopupMenuEvent
 
 class FilteringComboBoxTest {
 
@@ -552,6 +553,31 @@ class FilteringComboBoxTest {
         assertThat(comboBox.itemCount).isEqualTo(0)
     }
 
+    @Test
+    fun `#popupMenu does preserve selection when popup is closed without choosing`() {
+        // given
+        items.forEach { comboBox.addItem(it) }
+        SwingUtilities.invokeAndWait {
+            comboBox.selectedItem = items[2]
+        }
+        Thread.sleep(100)
+        val popupEvent = PopupMenuEvent(comboBox)
+
+        // when - open popup then close without selecting (same as clicking outside)
+        SwingUtilities.invokeAndWait {
+            comboBox.popupMenuListeners.forEach { listener ->
+                listener.popupMenuWillBecomeVisible(popupEvent)
+                listener.popupMenuWillBecomeInvisible(popupEvent)
+            }
+        }
+
+        // then
+        SwingUtilities.invokeAndWait {
+            assertThat(comboBox.selectedItem).isEqualTo(items[2])
+            assertThat(comboBox.selectedIndex).isGreaterThanOrEqualTo(0)
+        }
+    }
+
     @Test
     fun `#PopupOpened does handle programmatic popup opening vs user opening`() {
         // given