Bug Info:
=========
Mnemonic missing for the field(FolderName) when JFileChooser uses DIRECTORIES_ONLY mode and also tooltip shows 'Open selected file' instead of 'Open selected folder' while mouse rollover on button(Open).

JDK Info:
=========
java version "1.7.0-internal"
Java(TM) SE Runtime Environment (build 1.7.0-internal-jcg-integrator_18_Jun_2007_16_52-b00)
Java HotSpot(TM) Client VM (build 1.7.0-ea-b13, mixed mode)

Steps to Reproduce:
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1. Launch the filechooser demo.(${JAVA_HOME}/bin/java -jar ${JAVA_HOME}/demo/jfc/FileChooserDemo/FilChooserDemo.jar)
2. Select either metal or windows look and feel.
3. Select the 'Just Selected Directories' option in File and directories section.
4. Click on show file chooser button.

Expected Results:
=================
Folder name should have a mnenonic to choose the field by keyboard and should show the tooltip 'Open selected folder' while mouse over on Open button.

Actual Results:
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There is no mnemonic to choose the field by keyboard and it shows the tooltip 'Open selected file' instead while mouser over on Open button.