Comment 1 for bug 1715150

I can confirm this happens (in my case for png files - type of file should not matter though)
Steps to reproduce:
1. Open pinta as a regular user
2. Save the image to /usr/share/alsa/test.png
3. Unhandled exception is triggered:

System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> GLib.GException: Failed to open '/usr/share/alsa/test.png' for writing: Permission denied
  at Pinta.Actions.SaveDocumentImplmentationAction.SaveFile (Pinta.Core.Document document, System.String file, Pinta.Core.FormatDescriptor format, Gtk.Window parent) <0x4143a070 + 0x00513> in <filename unknown>:0
  at Pinta.Actions.SaveDocumentImplmentationAction.SaveFileAs (Pinta.Core.Document document) <0x41436260 + 0x00a4f> in <filename unknown>:0
  at Pinta.Actions.SaveDocumentImplmentationAction.Activated (System.Object sender, Pinta.Core.DocumentCancelEventArgs e) <0x41436130 + 0x0005b> in <filename unknown>:0
  at Pinta.Core.FileActions.RaiseSaveDocument (Pinta.Core.Document document, Boolean saveAs) <0x41435fe0 + 0x00075> in <filename unknown>:0
  at Pinta.Core.Document.Save (Boolean saveAs) <0x41435f90 + 0x00033> in <filename unknown>:0
  at Pinta.Actions.SaveDocumentAsAction.Activated (System.Object sender, System.EventArgs e) <0x41435f50 + 0x00027> in <filename unknown>:0
  at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (System.Reflection.MonoMethod,object,object[],System.Exception&)
  at System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) <0x7f7199dab9e0 + 0x000a1> in <filename unknown>:0