Fix terminal.integrated.rightClickCopyPaste on macOS

Fixes #25844

src/vs/workbench/parts/terminal/electron-browser/terminalInstance.ts

@@ -320,7 +320,7 @@ export class TerminalInstance implements ITerminalInstance {
 	}
 
 	public clearSelection(): void {
-		document.getSelection().empty();
+		window.getSelection().empty();
 	}
 
 	public dispose(): void {

src/vs/workbench/parts/terminal/electron-browser/terminalPanel.ts

@@ -172,6 +172,15 @@ export class TerminalPanel extends Panel {
 					} else {
 						terminal.paste();
 					}
+					// Clear selection after all click event bubbling is finished on Mac to prevent
+					// right-click selecting a word which is seemed cannot be disabled. There is a
+					// flicker when pasting but this appears to give the best experience if the
+					// setting is enabled.
+					if (platform.isMacintosh) {
+						setTimeout(() => {
+							terminal.clearSelection();
+						}, 0);
+					}
 					this._cancelContextMenu = true;
 				}
 			}