diff --git a/src/application/spriteOperations.ts b/src/application/spriteOperations.ts
index e1c5cc9..6552d6f 100644
--- a/src/application/spriteOperations.ts
+++ b/src/application/spriteOperations.ts
@@ -28,12 +28,23 @@ export function addSprites(newSprites: Sprite[]) {
       return;
     }
 
+    // Log the number of valid sprites being added
+    logger.info(`Adding ${validSprites.length} valid sprites`);
+
     sprites.value.push(...validSprites);
     sprites.value.sort((a, b) => a.uploadOrder - b.uploadOrder);
 
     // Update cell size before arranging sprites
+    logger.info('Updating cell size after adding sprites');
     updateCellSize();
-    autoArrangeSprites();
+
+    // Only auto-arrange if cell size is valid
+    if (cellSize && typeof cellSize.width === 'number' && typeof cellSize.height === 'number' && cellSize.width > 0 && cellSize.height > 0) {
+      logger.info('Auto-arranging sprites');
+      autoArrangeSprites();
+    } else {
+      logger.warn('Skipping auto-arrange due to invalid cell size');
+    }
   } catch (error) {
     logger.error('Error adding sprites:', error);
   }
@@ -44,12 +55,14 @@ export function addSprites(newSprites: Sprite[]) {
  */
 export function updateCellSize() {
   if (sprites.value.length === 0) {
+    logger.warn('Cannot update cell size: no sprites available');
     return;
   }
 
   try {
     let maxWidth = 0;
     let maxHeight = 0;
+    let validSpriteCount = 0;
 
     // Find the maximum dimensions across all sprites
     sprites.value.forEach(sprite => {
@@ -59,17 +72,29 @@ export function updateCellSize() {
       }
       maxWidth = Math.max(maxWidth, sprite.width);
       maxHeight = Math.max(maxHeight, sprite.height);
+      validSpriteCount++;
     });
 
-    if (maxWidth === 0 || maxHeight === 0) {
-      logger.error('Failed to calculate valid cell size');
+    if (maxWidth === 0 || maxHeight === 0 || validSpriteCount === 0) {
+      logger.error('Failed to calculate valid cell size - no valid sprites found');
       return;
     }
 
     // Add a small buffer to ensure sprites fit completely (optional)
     const buffer = 0; // Increase if you want padding between sprites
-    cellSize.width = maxWidth + buffer;
-    cellSize.height = maxHeight + buffer;
+
+    // Set cell size with validation
+    const newWidth = maxWidth + buffer;
+    const newHeight = maxHeight + buffer;
+
+    if (newWidth <= 0 || newHeight <= 0) {
+      logger.error(`Invalid calculated cell dimensions: ${newWidth}x${newHeight}`);
+      return;
+    }
+
+    logger.info(`Updating cell size to ${newWidth}x${newHeight}`);
+    cellSize.width = newWidth;
+    cellSize.height = newHeight;
 
     // Ensure all sprites are within their cell bounds after resize
     sprites.value.forEach((sprite, index) => {
@@ -100,13 +125,25 @@ export function updateCellSize() {
  */
 export function autoArrangeSprites() {
   if (sprites.value.length === 0) {
+    logger.warn('No sprites to arrange');
     return;
   }
 
   try {
-    if (cellSize.width <= 0 || cellSize.height <= 0) {
+    // Ensure cell size is valid before proceeding
+    if (!cellSize || typeof cellSize.width !== 'number' || typeof cellSize.height !== 'number' || cellSize.width <= 0 || cellSize.height <= 0) {
       logger.error('Invalid cell size for auto-arranging', cellSize);
-      return;
+
+      // Try to update cell size first
+      updateCellSize();
+
+      // Check again after update attempt
+      if (!cellSize || typeof cellSize.width !== 'number' || typeof cellSize.height !== 'number' || cellSize.width <= 0 || cellSize.height <= 0) {
+        logger.error('Still invalid cell size after update attempt', cellSize);
+        return;
+      }
+
+      logger.warn('Cell size was updated and is now valid');
     }
 
     // First update the canvas size to ensure it's large enough
diff --git a/src/application/utilities.ts b/src/application/utilities.ts
index 63ef55c..543108c 100644
--- a/src/application/utilities.ts
+++ b/src/application/utilities.ts
@@ -5,6 +5,9 @@ import { type Sprite } from '@/application/types';
  * Logger utility with consistent error format
  */
 export const logger = {
+  info: (message: string, details?: any) => {
+    console.log(`Spritesheet: ${message}`, details || '');
+  },
   warn: (message: string, details?: any) => {
     console.warn(`Spritesheet: ${message}`, details || '');
   },
diff --git a/src/components/DropZone.vue b/src/components/DropZone.vue
index 112ea5b..43a84b9 100644
--- a/src/components/DropZone.vue
+++ b/src/components/DropZone.vue
@@ -1,5 +1,12 @@
 <template>
-  <div @click="openFileDialog" @dragover.prevent="onDragOver" @dragleave="onDragLeave" @drop.prevent="onDrop" class="border-2 border-dashed border-gray-600 rounded-lg p-8 text-center cursor-pointer transition-all" :class="{ 'border-blue-500 bg-blue-500 bg-opacity-5': isDragOver }">
+  <div
+    @click="openFileDialog"
+    @dragover.prevent.stop="onDragOver"
+    @dragleave.prevent.stop="onDragLeave"
+    @drop.prevent.stop="onDrop"
+    class="border-2 border-dashed border-gray-600 rounded-lg p-8 text-center cursor-pointer transition-all"
+    :class="{ 'border-blue-500 bg-blue-500 bg-opacity-5': isDragOver }"
+  >
     <i class="fas fa-cloud-upload-alt text-blue-500 text-3xl mb-4"></i>
     <p class="text-gray-400">Drag & drop sprite images here<br />or click to select files</p>
     <input type="file" ref="fileInput" multiple accept="image/*" class="hidden" @change="onFileChange" />
@@ -37,6 +44,8 @@
     if (e.dataTransfer?.files.length) {
       handleFiles(e.dataTransfer.files);
     }
+    e.preventDefault();
+    e.stopPropagation();
   };
 
   const onFileChange = (e: Event) => {
diff --git a/src/components/MainContent.vue b/src/components/MainContent.vue
index 16971c5..69146b4 100644
--- a/src/components/MainContent.vue
+++ b/src/components/MainContent.vue
@@ -158,6 +158,9 @@
 
     if (!canvasEl.value) return;
 
+    // Prevent default to avoid any browser handling that might interfere
+    e.preventDefault();
+
     const rect = canvasEl.value.getBoundingClientRect();
     // Adjust coordinates for zoom level
     const x = (e.clientX - rect.left) / store.zoomLevel.value;
@@ -265,8 +268,14 @@
     }
   };
 
-  const handleMouseUp = () => {
+  const handleMouseUp = (e: MouseEvent) => {
     store.draggedSprite.value = null;
+
+    // Ensure the event is captured
+    if (e) {
+      e.preventDefault();
+      e.stopPropagation();
+    }
   };
 
   const handleMouseOut = () => {
@@ -322,14 +331,19 @@
       // Regular sprite dragging
       handleMouseDown(e);
     }
+
+    // Ensure the event is captured
+    e.stopPropagation();
   };
 
   /**
    * Handle mouse movement on the canvas for panning and sprite interactions
    */
   const handleCanvasMouseMove = (e: MouseEvent) => {
+    // Always prevent default to ensure consistent behavior
+    e.preventDefault();
+
     if (isPanning.value && containerEl.value) {
-      e.preventDefault();
       // Calculate the distance moved since last position
       const dx = e.clientX - lastPosition.value.x;
       const dy = e.clientY - lastPosition.value.y;
@@ -345,11 +359,18 @@
       // Handle regular mouse move for sprites and tooltip
       handleMouseMove(e);
     }
+
+    // Ensure the event is captured
+    e.stopPropagation();
   };
 
-  const handleCanvasMouseUp = () => {
+  const handleCanvasMouseUp = (e: MouseEvent) => {
     isPanning.value = false;
-    handleMouseUp();
+    handleMouseUp(e);
+
+    // Ensure the event is captured
+    e.preventDefault();
+    e.stopPropagation();
   };
 
   const handleCanvasMouseLeave = () => {
@@ -371,11 +392,15 @@
     }
 
     // Set up mouse events for the canvas
-    canvasEl.value.addEventListener('mousedown', handleCanvasMouseDown);
-    canvasEl.value.addEventListener('mousemove', handleCanvasMouseMove);
-    canvasEl.value.addEventListener('mouseup', handleCanvasMouseUp);
-    canvasEl.value.addEventListener('mouseleave', handleCanvasMouseLeave);
-    canvasEl.value.addEventListener('contextmenu', preventContextMenu);
+    canvasEl.value.addEventListener('mousedown', handleCanvasMouseDown, { passive: false });
+    canvasEl.value.addEventListener('mousemove', handleCanvasMouseMove, { passive: false });
+    canvasEl.value.addEventListener('mouseup', handleCanvasMouseUp, { passive: false });
+    canvasEl.value.addEventListener('mouseleave', handleCanvasMouseLeave, { passive: false });
+    canvasEl.value.addEventListener('contextmenu', preventContextMenu, { passive: false });
+
+    // Add global event listeners to ensure drag operations complete even if cursor leaves canvas
+    window.addEventListener('mousemove', handleCanvasMouseMove, { passive: false });
+    window.addEventListener('mouseup', handleCanvasMouseUp, { passive: false });
   };
 
   // Handle window resize to update canvas dimensions
@@ -467,6 +492,10 @@
         canvasEl.value.removeEventListener('mouseleave', handleCanvasMouseLeave);
         canvasEl.value.removeEventListener('contextmenu', preventContextMenu);
       }
+
+      // Remove global event listeners
+      window.removeEventListener('mousemove', handleCanvasMouseMove);
+      window.removeEventListener('mouseup', handleCanvasMouseUp);
     } catch (error) {
       logger.error('Error during component unmount:', error);
     }
diff --git a/src/components/PreviewModal.vue b/src/components/PreviewModal.vue
index a96d5f3..e65cbd1 100644
--- a/src/components/PreviewModal.vue
+++ b/src/components/PreviewModal.vue
@@ -27,8 +27,8 @@
             minHeight: `${store.cellSize.height * previewZoom}px`,
             cursor: previewZoom > 1 ? (isViewportDragging ? 'grabbing' : 'grab') : 'default',
           }"
-          @mousedown="e => startViewportDrag(e, isCanvasDragging)"
-          @wheel="handleCanvasWheel"
+          @mousedown.prevent="e => startViewportDrag(e, isCanvasDragging)"
+          @wheel.prevent="handleCanvasWheel"
         >
           <div
             class="sprite-wrapper"
@@ -47,7 +47,7 @@
               backgroundPosition: '0 0, 0 5px, 5px -5px, -5px 0px',
               backgroundColor: '#2d3748',
             }"
-            @mousedown.stop="e => startCanvasDrag(e, isViewportDragging, previewZoom)"
+            @mousedown.prevent.stop="e => startCanvasDrag(e, isViewportDragging, previewZoom)"
             title="Drag to move sprite within cell"
           >
             <canvas ref="animCanvas" class="block pixel-art absolute top-0 left-0"></canvas>
@@ -143,7 +143,9 @@
     await nextTick();
 
     // Ensure cell size is valid before proceeding
-    if (!store.cellSize || typeof store.cellSize.width !== 'number' || typeof store.cellSize.height !== 'number' || store.cellSize.width <= 0 || store.cellSize.height <= 0) {
+    if (!store.cellSize.value || typeof store.cellSize.value.width !== 'number' || typeof store.cellSize.value.height !== 'number' || store.cellSize.value.width <= 0 || store.cellSize.value.height <= 0) {
+      console.log('Attempting to update cell size...', store.cellSize.value);
+
       // Try to update cell size if there are sprites
       if (sprites.value.length > 0) {
         store.updateCellSize();
@@ -151,8 +153,12 @@
       }
 
       // Check again after update attempt
-      if (!store.cellSize || typeof store.cellSize.width !== 'number' || typeof store.cellSize.height !== 'number' || store.cellSize.width <= 0 || store.cellSize.height <= 0) {
+      if (!store.cellSize.value || typeof store.cellSize.value.width !== 'number' || typeof store.cellSize.value.height !== 'number' || store.cellSize.value.width <= 0 || store.cellSize.value.height <= 0) {
+        console.warn('Failed to set valid cell dimensions', store.cellSize.value);
         store.showNotification('Invalid cell dimensions. Please check sprite sizes.', 'error');
+        return; // Don't proceed if we can't set valid cell dimensions
+      } else {
+        console.log('Successfully updated cell size to', store.cellSize.value);
       }
     }
 
@@ -242,6 +248,24 @@
     }
   );
 
+  // Watch for changes in cellSize to update the canvas
+  watch(
+    () => store.cellSize.value,
+    newCellSize => {
+      if (isModalOpen.value && sprites.value.length > 0) {
+        if (newCellSize && typeof newCellSize.width === 'number' && typeof newCellSize.height === 'number' && newCellSize.width > 0 && newCellSize.height > 0) {
+          console.log('Cell size changed, updating canvas...', newCellSize);
+          updateCanvasSize();
+          updateCanvasContainerSize();
+          updateFrame();
+        } else {
+          console.warn('Invalid cell size detected in watcher', newCellSize);
+        }
+      }
+    },
+    { deep: true }
+  );
+
   // Expose openModal for external use
   defineExpose({ openModal });
 </script>
diff --git a/src/composables/useSpritePosition.ts b/src/composables/useSpritePosition.ts
index 65798bc..bef6b66 100644
--- a/src/composables/useSpritePosition.ts
+++ b/src/composables/useSpritePosition.ts
@@ -58,6 +58,13 @@ export function useSpritePosition(sprites: Ref<Sprite[]>, currentFrame: Ref<numb
     if (sprites.value.length === 0) return;
     if (isViewportDragging.value) return;
 
+    // Validate cell size before starting drag
+    if (!cellSize.value || typeof cellSize.value.width !== 'number' || typeof cellSize.value.height !== 'number' || cellSize.value.width <= 0 || cellSize.value.height <= 0) {
+      console.warn('Cannot start drag - invalid cell dimensions', cellSize.value ? `width: ${cellSize.value.width}, height: ${cellSize.value.height}` : 'cellSize is undefined');
+      showNotification('Cannot drag sprite - invalid cell dimensions', 'error');
+      return;
+    }
+
     isCanvasDragging.value = true;
 
     // Store initial position
@@ -66,9 +73,13 @@ export function useSpritePosition(sprites: Ref<Sprite[]>, currentFrame: Ref<numb
       y: e.clientY,
     };
 
-    // Add event listeners
-    window.addEventListener('mousemove', e => handleCanvasDrag(e, previewZoom), { capture: true });
-    window.addEventListener('mouseup', stopCanvasDrag, { capture: true });
+    // Add event listeners with passive: false to ensure preventDefault works
+    const boundHandleCanvasDrag = (e: MouseEvent) => handleCanvasDrag(e, previewZoom);
+    window.addEventListener('mousemove', boundHandleCanvasDrag, { capture: true, passive: false });
+    window.addEventListener('mouseup', stopCanvasDrag, { capture: true, passive: false });
+
+    // Store the bound function for later removal
+    (window as any).__boundHandleCanvasDrag = boundHandleCanvasDrag;
 
     e.preventDefault();
     e.stopPropagation();
@@ -82,9 +93,11 @@ export function useSpritePosition(sprites: Ref<Sprite[]>, currentFrame: Ref<numb
       const sprite = sprites.value[currentFrame.value];
       if (!sprite) return;
 
-      // Check if cellSize is properly defined
-      if (!cellSize.value || typeof cellSize.value.width !== 'number' || typeof cellSize.value.height !== 'number') {
-        console.warn('Invalid cell dimensions during drag operation');
+      // More robust check for cellSize validity
+      if (!cellSize.value || typeof cellSize.value.width !== 'number' || typeof cellSize.value.height !== 'number' || cellSize.value.width <= 0 || cellSize.value.height <= 0) {
+        console.warn('Invalid cell dimensions during drag operation', cellSize.value ? `width: ${cellSize.value.width}, height: ${cellSize.value.height}` : 'cellSize is undefined');
+        showNotification('Cannot drag sprite - invalid cell dimensions', 'error');
+        isCanvasDragging.value = false;
         return;
       }
 
@@ -127,9 +140,13 @@ export function useSpritePosition(sprites: Ref<Sprite[]>, currentFrame: Ref<numb
     if (!isCanvasDragging.value) return;
 
     isCanvasDragging.value = false;
-    window.removeEventListener('mousemove', handleCanvasDrag as any, { capture: true });
+    // Use the stored bound function for removal
+    window.removeEventListener('mousemove', (window as any).__boundHandleCanvasDrag, { capture: true });
     window.removeEventListener('mouseup', stopCanvasDrag, { capture: true });
 
+    // Clean up the reference
+    delete (window as any).__boundHandleCanvasDrag;
+
     e.preventDefault();
     e.stopPropagation();
   };
diff --git a/src/composables/useViewport.ts b/src/composables/useViewport.ts
index 9968fb6..4c854b6 100644
--- a/src/composables/useViewport.ts
+++ b/src/composables/useViewport.ts
@@ -56,9 +56,9 @@ export function useViewport(animation: Ref<AnimationState>, onUpdateFrame: () =>
       y: e.clientY,
     };
 
-    // Add temporary event listeners
-    window.addEventListener('mousemove', handleViewportDrag);
-    window.addEventListener('mouseup', stopViewportDrag);
+    // Add temporary event listeners with passive: false to ensure preventDefault works
+    window.addEventListener('mousemove', handleViewportDrag, { passive: false });
+    window.addEventListener('mouseup', stopViewportDrag, { passive: false });
 
     // Prevent default to avoid text selection
     e.preventDefault();
@@ -67,6 +67,10 @@ export function useViewport(animation: Ref<AnimationState>, onUpdateFrame: () =>
   const handleViewportDrag = (e: MouseEvent) => {
     if (!isViewportDragging.value) return;
 
+    // Prevent default browser behavior
+    e.preventDefault();
+    e.stopPropagation();
+
     const deltaX = e.clientX - viewportDragStart.value.x;
     const deltaY = e.clientY - viewportDragStart.value.y;
 
@@ -83,10 +87,18 @@ export function useViewport(animation: Ref<AnimationState>, onUpdateFrame: () =>
     };
   };
 
-  const stopViewportDrag = () => {
+  const stopViewportDrag = (e: MouseEvent) => {
+    if (!isViewportDragging.value) return;
+
     isViewportDragging.value = false;
     window.removeEventListener('mousemove', handleViewportDrag);
     window.removeEventListener('mouseup', stopViewportDrag);
+
+    // Prevent default browser behavior
+    if (e) {
+      e.preventDefault();
+      e.stopPropagation();
+    }
   };
 
   const handleCanvasWheel = (e: WheelEvent) => {