deryaaltuntas ,
Sorry that you are seeing this issue. I could not replicate the issue at my end.
Can you answer some more questions for us ?
1) Can you share the Installation Details from MyEclipse > Installation Summary > Installation Details ? Paste them here.
2) Clear the contents of the .log file which is located at <workspace dir>/.metadata/.log, replicate the issue and check if you see any errors of interest in the .log file. If yes then paste the entire error here.
3) Can you check if you see the same issue with a newly created Matisse form ? Create a Matisse form and drop a swing control to check if the issue persists.