allow left-button-release to copy to selection when shift is held

This is really a timing issue: if shift-click extension of the mouse
selection is used, the user may release the mouse button slightly
after the SHIFT key (which is fine) or vice versa (which was not
previously matched)

refs: #1204

config/src/keyassignment.rs

@@ -510,6 +510,16 @@ impl InputMap {
                     },
                     ExtendSelectionToMouseCursor(None)
                 ],
+                [
+                    Modifiers::SHIFT,
+                    MouseEventTrigger::Up {
+                        streak: 1,
+                        button: MouseButton::Left
+                    },
+                    CompleteSelectionOrOpenLinkAtMouseCursor(
+                        ClipboardCopyDestination::PrimarySelection
+                    )
+                ],
                 [
                     Modifiers::NONE,
                     MouseEventTrigger::Up {

docs/changelog.md

@@ -26,6 +26,7 @@ As features stabilize some brief notes about them will accumulate here.
 #### Changed
 
 * quickselect: we now de-duplicate labels for results with the same textual content. [#1271](https://github.com/wez/wezterm/issues/1271)
+* The default `CompleteSelectionOrOpenLinkAtMouseCursor` left button release assignment now also accepts SHIFT being held in order to make SHIFT-click `ExtendSelectionToMouseCursor` feel more ergonomic if the mouse button is released before the SHIFT key. [#1204](https://github.com/wez/wezterm/issues/1204)
 
 #### Updated and Improved
 

docs/config/mouse.md

@@ -32,6 +32,7 @@ that order.
 | Double Left Down | `NONE`   | `SelectTextAtMouseCursor="Word"`  |
 | Single Left Down | `NONE`   | `SelectTextAtMouseCursor="Cell"`  |
 | Single Left Down | `SHIFT`   | `ExtendSelectionToMouseCursor={}`  |
+| Single Left Up | `SHIFT`   | `CompleteSelectionOrOpenLinkAtMouseCursor="PrimarySelection"`  |
 | Single Left Up | `NONE`   | `CompleteSelectionOrOpenLinkAtMouseCursor="PrimarySelection"`  |
 | Double Left Up | `NONE`   | `CompleteSelection="PrimarySelection"`  |
 | Triple Left Up | `NONE`   | `CompleteSelection="PrimarySelection"`  |