Fix Shift+Click on Canvas Selecting Text in Panels (#1347)

## Description

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Fixes an issue where if the previous selection or active element was inside the sidebar or context panel a shift + click operation on the canvas would select content in that panel instead of on the canvas.

## Related Issue and Pull requests

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## Type of Change

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- [x] Bug fix

## Checklist

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- [ ] I have tested this does not break current pipelines / runs functionality
- [ ] I have tested the changes on staging

## Screenshots (if applicable)

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## Test Instructions

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HOW TO REPRODUCE THE ORIGINAL BUG
go on master branch:
1. click inside the sidebar or context panel
2. shift + drag to select nodes on the canvas
3. text in the panel you click on should be selected

bad!

HOW TO TEST THAT IT'S FIXED
switch to the branch for this PR
1. repeat the steps above
2. text in the panel should no longer get selected - only the nodes you've chosen

good!

## Additional Comments

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Author: camielvs

src/components/shared/ReactFlow/FlowCanvas/FlowCanvas.tsx

@@ -227,15 +227,26 @@ const FlowCanvas = ({
     }
   }, []);
 
+  const handleMouseDown = useCallback((event: MouseEvent) => {
+    if (event.shiftKey && event.target instanceof HTMLElement) {
+      const reactFlowWrapper = event.target.closest(".react-flow");
+      if (reactFlowWrapper) {
+        event.preventDefault();
+      }
+    }
+  }, []);
+
   useEffect(() => {
     document.addEventListener("keydown", handleKeyDown);
     document.addEventListener("keyup", handleKeyUp);
+    document.addEventListener("mousedown", handleMouseDown);
 
     return () => {
       document.removeEventListener("keydown", handleKeyDown);
       document.removeEventListener("keyup", handleKeyUp);
+      document.removeEventListener("mousedown", handleMouseDown);
     };
-  }, [handleKeyDown, handleKeyUp]);
+  }, [handleKeyDown, handleKeyUp, handleMouseDown]);
 
   const [reactFlowInstance, setReactFlowInstance] =
     useState<ReactFlowInstance>();