Dragging item from archiver onto pcmanfm's side pane freezes the archiver

[CasperVector]

• Open pcmanfm with the side pane enabled, open a compressed file with engrampa, and drag an item from the compressed file across the side pane.
• As soon as the mouse pointer reaches the side pane, even before the item is dropped, an error dialog shows up; meanwhile, the shape of the pointer changes from the normal "hand" (if originally outside of the file list area in pcmanfm) or the "hand with plus sign" (if originally inside the file list) to the "hand with chain sign".
• The desktop becomes unresponsive to mouse clicks and most keystrokes, until engrampa is killed, after which the pointer shape returns normal. Similar symptom also happens with xarchiver, but not with thunar.
• The issue can be worked around by reverting the changes in 1d7738c; actually, disabling the if(!dd->waiting_data) { ... } branch when either dest or dest_path is zero prevents the symptom from occuring. However, I am totally unfamiliar with the drag-and-drop protocols, and therefore unsure whether this fixes the root cause of this issue and does not cause undesirable side effects.

[CasperVector]

A patch which seems most unintrusive to me:

diff -ur libfm-1.3.2/src/gtk/fm-dnd-dest.c libfm-1.3.2/src/gtk/fm-dnd-dest.c
--- libfm-1.3.2/src/gtk/fm-dnd-dest.c	2022-10-31 01:05:49.931057670 +0800
+++ libfm-1.3.2/src/gtk/fm-dnd-dest.c	2022-10-31 01:07:27.667579011 +0800
@@ -979,7 +979,7 @@
         if (dd->context != drag_context)
             clear_src_cache(dd);
         action = 0;
-        if(!dd->waiting_data) /* we're still waiting for "drag-data-received" signal */
+        if(dest_path && !dd->waiting_data) /* we're still waiting for "drag-data-received" signal */
         {
             /* retrieve the source files */
             gtk_drag_get_data(dd->widget, drag_context, target, time(NULL));

[CasperVector]

Sorry, incomplete check...

diff -ur libfm-1.3.2/src/gtk/fm-dnd-dest.c libfm-1.3.2/src/gtk/fm-dnd-dest.c
--- libfm-1.3.2/src/gtk/fm-dnd-dest.c	2022-10-31 01:05:49.931057670 +0800
+++ libfm-1.3.2/src/gtk/fm-dnd-dest.c	2022-10-31 01:07:27.667579011 +0800
@@ -979,7 +979,7 @@
         if (dd->context != drag_context)
             clear_src_cache(dd);
         action = 0;
-        if(!dd->waiting_data) /* we're still waiting for "drag-data-received" signal */
+        if(dest && dest_path && !dd->waiting_data) /* we're still waiting for "drag-data-received" signal */
         {
             /* retrieve the source files */
             gtk_drag_get_data(dd->widget, drag_context, target, time(NULL));

[dirkf]

Did you build and test this? It doesn't seem to have a PR yet.

[cwendling]

@CasperVector it probably will work, but doesn't that just effectively revert 1d7738c? I'm not sure the reason behind that commit, and it's from 2012, but it sill might be interesting to see why that was done like so.