XnView Software

My husband and I both installed XnView v. 0.35 on our Macs yesterday. Mine still looks normal with the regular Mac toolbar at the top and showing the red, yellow and green buttons. On my husband's Mac, he can't see these areas. To get to the toolbar, he has to move his mouse to the top of his screen ...

I'm new to Macs and new to XnView. I installed XnViewMP v. 0.35 beta today. It seems to be working just fine, but my problem it totally of my own making. In looking around the window as it first opens, I accidentally clicked to close the preview window. I couldn't find any way to get it back and now ...