Cause: The Window Class `RunLoopMessageWindow` is never registered (this happens because registerRunLoopMessageWindowClass() is moved to MainThreadWin.cpp while openjfx uses MainThreadJava.cpp) and this causes every setTimer() to create a new user object instead of reusing the same object over again.
Fix: Call registerRunLoopMessageWindowClass() from MainThreadJava.cpp Test: To verify open any webpage using WebView on WIndows, with and without the fix and compare the number of user objects created using Windows Task Manager. ------------- Commit messages: - 8244579: Windows "User Objects" leakage with WebView Changes: https://git.openjdk.java.net/jfx/pull/229/files Webrev: https://webrevs.openjdk.java.net/jfx/229/webrev.00 Issue: https://bugs.openjdk.java.net/browse/JDK-8244579 Stats: 4 lines in 1 file changed: 4 ins; 0 del; 0 mod Patch: https://git.openjdk.java.net/jfx/pull/229.diff Fetch: git fetch https://git.openjdk.java.net/jfx pull/229/head:pull/229 PR: https://git.openjdk.java.net/jfx/pull/229