+ New feauture from wishlist: drag'n'drop pictures from web browser\n* F...

Pinta.Core/Classes/DocumentWorkspace.cs

@@ -194,6 +194,9 @@ public void ScrollCanvas (int dx, int dy)
 		/// </param>
 		public Cairo.PointD WindowPointToCanvas (double x, double y)
 		{
+			if (PintaCore.Workspace.HasOpenPendingDocuments)
+				return new Cairo.PointD();
+
 			ScaleFactor sf = new ScaleFactor (PintaCore.Workspace.ImageSize.Width,
 			                                  PintaCore.Workspace.CanvasSize.Width);
 			Cairo.PointD pt = sf.ScalePoint (new Cairo.PointD (x - Offset.X, y - Offset.Y));

Pinta.Core/Classes/ScaleFactor.cs

@@ -362,11 +362,11 @@ public static ScaleFactor FromDouble (double scalar)
 		public ScaleFactor (int numerator, int denominator)
 		{
 			if (denominator <= 0) {
-				throw new ArgumentOutOfRangeException ("denominator", "must be greater than 0");
+				throw new ArgumentOutOfRangeException ("denominator", "must be greater than 0(denominator = " + denominator + ")");
 			}
 
 			if (numerator < 0) {
-				throw new ArgumentOutOfRangeException ("numerator", "must be greater than 0");
+				throw new ArgumentOutOfRangeException ("numerator", "must be greater than 0(numerator = " + numerator + ")");
 			}
 
 			this.numerator = numerator;

Pinta.Core/Managers/WorkspaceManager.cs

@@ -37,6 +37,7 @@ public class WorkspaceManager
 	{
 		private int active_document_index = -1;
 		private int new_file_name = 1;
+		private bool has_open_pending_documents = false; // If there is an ongoing open document operation
 
 		public event EventHandler SelectionChanged;
 
@@ -95,6 +96,11 @@ public void CallSelectionChanged(object sender, EventArgs e)
 
 		public List<Document> OpenDocuments { get; private set; }
 		public bool HasOpenDocuments { get { return OpenDocuments.Count > 0; } }
+
+		public bool HasOpenPendingDocuments {
+			get { return this.has_open_pending_documents; }
+			set { this.has_open_pending_documents = value; }
+		}
 
 		public Document CreateAndActivateDocument (string filename, Gdk.Size size)
 		{

Pinta.Gui.Widgets/Widgets/OpenImages/OpenImagesListWidget.cs

@@ -142,6 +142,9 @@ void HandleTreeButtonPressEvent (object o, ButtonPressEventArgs args)
 				TreePath path;
 				tree.GetPathAtPos ((int)click_x, (int)click_y, out path);
 
+				if (path == null)
+					return;
+
 				PintaCore.Workspace.SetActiveDocument (path.Indices[0]);
 				PintaCore.Actions.File.Close.Activate ();
 				UpdateSelectedDocument ();

Pinta/MainWindow.cs

@@ -399,11 +399,36 @@ private void MainWindow_DragDataReceived (object o, DragDataReceivedArgs args)
 
 			string fullData = System.Text.Encoding.UTF8.GetString (args.SelectionData.Data);
 
-			foreach (string individualFile in fullData.Split ('\n')) {
-				string file = individualFile.Trim ();
+			try {
+				PintaCore.Workspace.HasOpenPendingDocuments = true;
 
-				if (file.StartsWith ("file://"))
-					PintaCore.Workspace.OpenFile (new Uri (file).LocalPath);
+				foreach (string individualFile in fullData.Split ('\n')) {
+					string file = individualFile.Trim ();
+					Console.WriteLine (file);
+
+					if (file.StartsWith ("http")) {
+						System.Net.WebClient client = new System.Net.WebClient ();
+						string tempFilePath = System.IO.Path.GetTempPath () + System.IO.Path.GetFileName(file);
+
+						Console.WriteLine (">>File downloaded; " + file + "; " + tempFilePath);
+
+						try {
+							client.DownloadFile (file, @tempFilePath);
+						} finally {
+							client.Dispose ();
+						}
+
+						if (System.IO.File.Exists (tempFilePath))
+							file = "file://" + tempFilePath;
+						else
+							Console.WriteLine ("Unable to download target file: " + tempFilePath);
+					}
+
+					if (file.StartsWith ("file://"))
+						PintaCore.Workspace.OpenFile (new Uri (file).LocalPath);
+				}
+			} finally {
+				PintaCore.Workspace.HasOpenPendingDocuments = false;
 			}
 		}