New file selection prompt is slower than before

[charlestian23]

Current Behavior

If you go on dev and compile a jar file, and then attempt to open a file, you'll see that the prompt takes a slight moment before it shows up. However, if you go to recent releases and download Legup 4.0.0 beta and then attempt to open a file, you'll see that the Windows-styled prompt shows up almost instantaneously.

Expected Behavior

The Java-styled prompt on dev should show up almost instantaneously.

Steps to reproduce

1. Go to dev and compile a jar file
2. Click on the prompt to open a file