IDEA-95136 Move to another changelist shall pre-select 'create new' option If there's only one changelist so far [r=vasya]

platform/testFramework/testSrc/com/intellij/testFramework/vcs/MockChangeListManager.java

@@ -71,6 +71,11 @@ public class MockChangeListManager extends ChangeListManagerEx {
     throw new UnsupportedOperationException();
   }
 
+  @Override
+  public int getChangeListsNumber() {
+    return getChangeListsCopy().size();
+  }
+
   @Override
   public List<LocalChangeList> getChangeListsCopy() {
     return new ArrayList<LocalChangeList>(myChangeLists.values());

platform/vcs-api/src/com/intellij/openapi/vcs/changes/ChangeListManager.java

@@ -51,6 +51,7 @@ public abstract class ChangeListManager implements ChangeListModification {
   @TestOnly
   public abstract boolean ensureUpToDate(boolean canBeCanceled);
 
+  public abstract int getChangeListsNumber();
   public abstract List<LocalChangeList> getChangeListsCopy();
   @NotNull
   public abstract List<LocalChangeList> getChangeLists();

platform/vcs-impl/src/com/intellij/openapi/vcs/changes/ChangeListManagerImpl.java

@@ -1410,6 +1410,13 @@ public class ChangeListManagerImpl extends ChangeListManagerEx implements Projec
     return worker.isDone();
   }
 
+  @Override
+  public int getChangeListsNumber() {
+    synchronized (myDataLock) {
+      return myWorker.getChangeListsNumber();
+    }
+  }
+
   // only a light attempt to show that some dirty scope request is asynchronously coming
   // for users to see changes are not valid
   // (commit -> asynch synch VFS -> asynch vcs dirty scope)

platform/vcs-impl/src/com/intellij/openapi/vcs/changes/ChangeListWorker.java

@@ -549,6 +549,10 @@ public class ChangeListWorker implements ChangeListsWriteOperations {
     return changes;
   }
 
+  public int getChangeListsNumber() {
+    return myMap.size();
+  }
+
   private abstract class ExternalVsInternalChangesIntersection {
     protected final Collection<Change> myInChanges;
     protected final Map<Pair<String, String>, LocalChangeList> myInternalMap;

platform/vcs-impl/src/com/intellij/openapi/vcs/changes/ui/ChangeListChooser.java

@@ -17,10 +17,7 @@ package com.intellij.openapi.vcs.changes.ui;
 
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.ui.DialogWrapper;
-import com.intellij.openapi.vcs.changes.ChangeList;
-import com.intellij.openapi.vcs.changes.ChangeListEditHandler;
-import com.intellij.openapi.vcs.changes.LocalChangeList;
-import com.intellij.openapi.vcs.changes.LocalChangeListImpl;
+import com.intellij.openapi.vcs.changes.*;
 import com.intellij.util.NullableConsumer;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -61,7 +58,7 @@ public class ChangeListChooser extends DialogWrapper {
 
     myPanel.init();
     myPanel.setChangeLists(changelists);
-    myPanel.setDefaultSelection(defaultSelection);
+    myPanel.setDefaultSelection(changelists.size() <= 1 && onlyOneListInProject() ? null : defaultSelection);
 
     setTitle(title);
     if (defaultName != null) {
@@ -71,6 +68,10 @@ public class ChangeListChooser extends DialogWrapper {
     init();
   }
 
+  private boolean onlyOneListInProject() {
+    return ChangeListManager.getInstance(myProject).getChangeListsNumber() <= 1;
+  }
+
   public JComponent getPreferredFocusedComponent() {
     return myPanel.getPreferredFocusedComponent();
   }