How to resize dialog dynamically?

[Mikl__]

NoCforMe
Thanks for your comments! You can click on the "Close" button, then the "Open" button will be activated.

[NoCforMe]

Right, I saw that.
Every application I have that does thing like this (open a file to play, audio or video) lets you open a new file while another one is playing without having to "close" it. (Of course it has to close it internally.)

[Mikl__]

This is my first experience in writing a media player. I will try to find and correct such errors. Don't judge too harshly 

[NoCforMe]

No, no, you're doing fine. Keep it up!