make fabs to AppBar icon buttons

lib/sheet_viewer_page.dart

@@ -75,7 +75,35 @@ class _SheetViewerPageState extends State<SheetViewerPage> {
   @override
   Widget build(BuildContext context) {
     return Scaffold(
-      appBar: AppBar(title: Text(widget.sheet.name)),
+      appBar: AppBar(
+        title: Text(widget.sheet.name),
+        actions: [
+          IconButton(
+            onPressed: () {
+              setState(() {
+                if (twoPageMode) {
+                  // TODO: notification that paint mode only in single page mode
+                } else {
+                  paintMode = !paintMode;
+                }
+              });
+            },
+            icon: Icon(Icons.brush),
+          ),
+          IconButton(
+            onPressed: () {
+              setState(() {
+                twoPageMode = !twoPageMode;
+                if (twoPageMode) {
+                  paintMode = false;
+                  // TODO: notification that paint mode was deactivated since only possible in single page mode
+                }
+              });
+            },
+            icon: Icon(twoPageMode ? Icons.filter_1 : Icons.filter_2),
+          ),
+        ],
+      ),
       body: FutureBuilder(
         future: documentLoaded,
         builder: (BuildContext context, AsyncSnapshot<bool> snapshot) {
@@ -211,42 +239,6 @@ class _SheetViewerPageState extends State<SheetViewerPage> {
                     ),
                   ],
                 ),
-                Container(
-                  alignment: Alignment.bottomLeft,
-                  margin: EdgeInsets.all(10),
-                  child: Column(
-                    spacing: 10,
-                    mainAxisAlignment: MainAxisAlignment.end,
-                    children: [
-                      FloatingActionButton(
-                        onPressed: () {
-                          setState(() {
-                            if (twoPageMode) {
-                              // TODO: notification that paint mode only in single page mode
-                            } else {
-                              paintMode = !paintMode;
-                            }
-                          });
-                        },
-                        child: Icon(Icons.brush),
-                      ),
-                      FloatingActionButton(
-                        onPressed: () {
-                          setState(() {
-                            twoPageMode = !twoPageMode;
-                            if (twoPageMode) {
-                              paintMode = false;
-                              // TODO: notification that paint mode was deactivated since only possible in single page mode
-                            }
-                          });
-                        },
-                        child: Icon(
-                          twoPageMode ? Icons.filter_1 : Icons.filter_2,
-                        ),
-                      ),
-                    ],
-                  ),
-                ),
               ],
             );
           } else if (snapshot.hasError) {