A component with custom renderer placed in JScrollPane is being passed a Graphics object with incorrectly initialized FontMetrics during scrolling. Standard paints get correct FontMetrics, paints initiated from scrolling operations don't. I'll attach a simple test case that demonstrates the problem. It works correctly on JDK 1.4.2 and 5.0. It fails on Mustang.
This seems to be the root cause of NetBeans bug #51731:
first time reported against Mustang b13, reliably reproducible since then until b53.
The same bug was reported against Mustang as #6307484. Closed as 'not reproducible'. I believe that the attached test case points to a Mustang issue.
The attached test case shows a JFrame containing a standard JList with a custom cell renderer. Custom font is set to Monospaced, 11pt. The initial paint works ok. The problem occurs when I start to scroll the JList content using the scroll bar. The debug getFontMetrics() dump shows that different FontMetrics are being passed in the "standard" and "scrolling" scenarios.