private void OpenFilesCommand_Execute()
{
var dialog = new OpenFileDialog
{
Multiselect = true,
Filter = "PDF files (*.pdf) | *.pdf"
};
if (dialog.ShowDialog() == true)
{
PdfFiles.AddRange(dialog.FileNames);
}
ExtractImagesCommand?.RaiseCanExecuteChanged();
ClearFilesCommand?.RaiseCanExecuteChanged();
}