According to d1's Mono report...
Deal breakers:
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Line 470 of Form1.cs
this.pictPreview.ImageLocation = (string)this.lstFiles.SelectedItem

That tells the PictureBox control to use the file path, which is selected in the ListBox control, as the location of the image to display. You can get rid of this line, but the image preview functionality will be completely broken.
If you find the property of the PictureBox control that allows setting the location of the image to display, then replace "this.pictPreview.ImageLocation = " with it.
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Line 507 of Form1.cs
this.pictPreview.ImageLocation = "";

Same deal as above. But... you can delete this line without any functionality lost - this line just clears the picture preview so that no image is displayed. When you delete this, the picture preview will just display a picture that isn't in the ListBox anymore.
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It starts at Line 105 of Form1.cs.

There's code to call "explorer.exe" with "/select "path to a file"" that'd need to be written specifically for whatever file manager/viewer you desire using. You'll probably get error pop ups from your OS about not finding "explorer.exe" when this code is invoked.

It could just be removed, it's not critical to the program - it's a convenience feature.
It's meant to open up Windows Explorer when you right click a file name in the ListBox.

Also in that area of code, it prints out "Windows Explorer launched", so you may want to change that text.
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