fix look and feel of toolbar on Metal (Ubuntu)

Look and feel tested on
- macOS (Oracle, Mac OS X)
- Windows 10 (Oracle, Windows)
- Ubuntu (Oracle, Metal)

Author: PhilippSalvisberg

sqldev/src/main/java/org/utplsql/sqldev/ui/runner/GradientToolbar.xtend

@@ -19,38 +19,67 @@ import java.awt.Color
 import java.awt.GradientPaint
 import java.awt.Graphics
 import java.awt.Graphics2D
+import java.awt.Insets
 import javax.swing.JToolBar
+import javax.swing.UIManager
+import javax.swing.border.BevelBorder
+import javax.swing.border.EmptyBorder
 
 class GradientToolbar extends JToolBar { 
+
+	private def isOracleLookAndFeel() {
+		val laf = UIManager.lookAndFeel?.name
+		if (laf == "Oracle Look and Feel version 2") {
+			return true
+		} else {
+			return false
+		}		
+	}
+	
+	new() {
+		super()
+		if (oracleLookAndFeel) {
+			this.border = new EmptyBorder(new Insets(2, 2, 2, 2)) // top, left, bottom, right
+		} else {
+			this.border =  new BevelBorder(BevelBorder.RAISED)
+		}
+	}
+
 	override paintComponent(Graphics g) {
-		// default for non-opaque components
-		if (!opaque) {
+		if (oracleLookAndFeel) {
+			// emulate Oracle toolbar
+			// 1. default for non-opaque components
+			if (!opaque) {
+				super.paintComponent(g)
+				return
+			}
+			
+			// 2. paint gradient background from top to bottom with separator line at the bottom
+			val g2d = g as Graphics2D
+			val w = width
+	        val h = height - 1
+	        val h2 = height / 2 as int
+	        val colorTop = new Color(237, 237, 237)
+	        val colorMiddle = new Color(244, 244, 244)
+	        val colorBottom = new Color(254, 254, 254)
+	        val colorBottomLine = Color.LIGHT_GRAY
+	        val gp1 = new GradientPaint(0, 0, colorTop, 0, h2, colorMiddle)
+	        g2d.paint = gp1
+	        g2d.fillRect(0, 0, w, h2)
+	        val gp2 = new GradientPaint(0, h2, colorMiddle, 0, h, colorBottom)
+	        g2d.paint = gp2
+	        g2d.fillRect(0, h2, w, h)
+	        g2d.paint = colorBottomLine
+	        g2d.fillRect(0, h, w, h+1)
+			
+			// 3. do rest, changing opaque to ensure background is not overwritten
+			setOpaque(false)
+			super.paintComponent(g)
+			setOpaque(true)
+		} else {
+			// default logic
 			super.paintComponent(g)
-			return
 		}
-		
-		// paint gradient background from top to bottom with separator line at the bottom
-		val g2d = g as Graphics2D
-		val w = width
-        val h = height - 1
-        val h2 = height / 2 as int
-        val colorTop = new Color(237, 237, 237)
-        val colorMiddle = new Color(244, 244, 244)
-        val colorBottom = new Color(254, 254, 254)
-        val colorBottomLine = Color.LIGHT_GRAY
-        val gp1 = new GradientPaint(0, 0, colorTop, 0, h2, colorMiddle)
-        g2d.paint = gp1
-        g2d.fillRect(0, 0, w, h2)
-        val gp2 = new GradientPaint(0, h2, colorMiddle, 0, h, colorBottom)
-        g2d.paint = gp2
-        g2d.fillRect(0, h2, w, h)
-        g2d.paint = colorBottomLine
-        g2d.fillRect(0, h, w, h+1)
-		
-		// do rest, changing opaque to ensure background is not overwritten
-		setOpaque(false)
-		super.paintComponent(g)
-		setOpaque(true)
 	}
 
 }

sqldev/src/main/java/org/utplsql/sqldev/ui/runner/RunnerPanel.xtend

@@ -726,17 +726,20 @@ class RunnerPanel implements ActionListener, MouseListener, HyperlinkListener {
 		// Toolbar
 		var toolbar = new GradientToolbar
 		toolbar.floatable = false
-		toolbar.border = new EmptyBorder(new Insets(2, 2, 2, 2)) // top, left, bottom, right
+		val buttonBorder = new EmptyBorder(new Insets(2, 4, 2, 4)) // top, left, bottom, right
 		refreshButton = new ToolbarButton(UtplsqlResources.getIcon("REFRESH_ICON"))
 		refreshButton.toolTipText = UtplsqlResources.getString("RUNNER_REFRESH_TOOLTIP")
+		refreshButton.border = buttonBorder
 		refreshButton.addActionListener(this)
 		toolbar.add(refreshButton)
 		rerunButton = new ToolbarButton(UtplsqlResources.getIcon("RUN_ICON"))
 		rerunButton.toolTipText = UtplsqlResources.getString("RUNNER_RERUN_TOOLTIP")
+		rerunButton.border = buttonBorder
 		rerunButton.addActionListener(this)
 		toolbar.add(rerunButton)
 		rerunWorksheetButton = new ToolbarButton(UtplsqlResources.getIcon("RUN_WORKSHEET_ICON"))
 		rerunWorksheetButton.toolTipText = UtplsqlResources.getString("RUNNER_RERUN_WORKSHEET_TOOLTIP")
+		rerunWorksheetButton.border = buttonBorder
 		rerunWorksheetButton.addActionListener(this)
 		toolbar.add(rerunWorksheetButton)
 		toolbar.add(Box.createHorizontalGlue())
@@ -749,6 +752,7 @@ class RunnerPanel implements ActionListener, MouseListener, HyperlinkListener {
 		toolbar.add(runComboBox)
 		clearButton = new ToolbarButton(UtplsqlResources.getIcon("CLEAR_ICON"))
 		clearButton.toolTipText = UtplsqlResources.getString("RUNNER_CLEAR_HISTORY_BUTTON")
+		clearButton.border = buttonBorder
 		clearButton.addActionListener(this)
 		toolbar.add(clearButton)
 		c.gridx = 0