ToolTip: do not show empty tooltip component if tooltip text is an empty string (issue #134)

CHANGELOG.md

@@ -12,6 +12,8 @@ FlatLaf Change Log
   "JScrollPane.smoothScrolling" is set to a `Boolean` on `JScrollPane`.
 - ScrollBar: Increased minimum thumb size on macOS and Linux from 8 to 18
   pixels. On Windows, it is now 10 pixels. (issue #131)
+- ToolTip: Do not show empty tooltip component if tooltip text is an empty
+  string. (issue #134)
 
 
 ## 0.38

flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatToolTipUI.java

@@ -94,6 +94,11 @@ public class FlatToolTipUI
 
 	@Override
 	public Dimension getPreferredSize( JComponent c ) {
+		// do not show tool tip if text is empty
+		String text = ((JToolTip)c).getTipText();
+		if( text == null || text.isEmpty() )
+			return new Dimension();
+
 		if( isMultiLine( c ) ) {
 			FontMetrics fm = c.getFontMetrics( c.getFont() );
 			Insets insets = c.getInsets();