diff --git a/src/project.ts b/src/project.ts
index 8a3a75c5..e79894c9 100644
--- a/src/project.ts
+++ b/src/project.ts
@@ -32,22 +32,26 @@ export class CodeProject {
     this.store = store;
 
     worker.onmessage = (e) => {
-      var notfinal = this.pendingWorkerMessages > 1;
-      if (notfinal) {
-        this.sendBuild();
-        this.pendingWorkerMessages = 1;
-      } else {
-        if (this.callbackBuildStatus) this.callbackBuildStatus(false);
-        if (!this.isCompiling) { console.log(this.pendingWorkerMessages); console.trace(); } // debug compile problems
-        this.isCompiling = false;
-        this.pendingWorkerMessages = 0;
-      }
-      if (e.data && !e.data.unchanged) {
-        this.processBuildResult(e.data);
-        if (this.callbackBuildResult) this.callbackBuildResult(e.data); // call with data when changed
-      }
+      this.receiveWorkerMessage(e.data);
     };
   }
+  
+  receiveWorkerMessage(data : WorkerResult) {
+    var notfinal = this.pendingWorkerMessages > 1;
+    if (notfinal) {
+      this.sendBuild();
+      this.pendingWorkerMessages = 1;
+    } else {
+      if (this.callbackBuildStatus) this.callbackBuildStatus(false);
+      if (!this.isCompiling) { console.log(this.pendingWorkerMessages); console.trace(); } // debug compile problems
+      this.isCompiling = false;
+      this.pendingWorkerMessages = 0;
+    }
+    if (data && !data.unchanged) {
+      this.processBuildResult(data);
+      if (this.callbackBuildResult) this.callbackBuildResult(data); // call with data when changed
+    }
+  }
 
   preloadWorker(path:string) {
     var tool = this.platform.getToolForFilename(path);
@@ -235,6 +239,19 @@ export class CodeProject {
   sendBuild() {
     if (!this.mainpath) throw "need to call setMainFile first";
     var maindata = this.getFile(this.mainpath);
+    // if binary blob, just return it as ROM
+    if (maindata instanceof Uint8Array) {
+      this.isCompiling = true;
+      this.receiveWorkerMessage({
+        output:maindata,
+        errors:[],
+        listings:null,
+        symbolmap:null,
+        params:{}
+      });
+      return;
+    }
+    // otherwise, make it a string
     var text = typeof maindata === "string" ? maindata : '';
     // TODO: load dependencies of non-main files
     this.loadFileDependencies(text, (err, depends) => {
diff --git a/src/ui.ts b/src/ui.ts
index f223f1d1..6f64dfa3 100644
--- a/src/ui.ts
+++ b/src/ui.ts
@@ -206,7 +206,6 @@ function loadProject(preset_id:string) {
       alert(err);
     } else if (result && result.length) {
       // we need this to build create functions for the editor
-      // TODO: can't use binary file as main
       refreshWindowList();
       // show main file
       projectWindows.createOrShow(preset_id);
diff --git a/src/views.ts b/src/views.ts
index 575afb1d..31293110 100644
--- a/src/views.ts
+++ b/src/views.ts
@@ -25,7 +25,6 @@ export interface ProjectView {
   setTimingResult?(result:CodeAnalyzer) : void;
 };
 
-// TODO: move to different namespace
 declare var CodeMirror;
 declare var VirtualList;
 
@@ -36,8 +35,9 @@ function jumpToLine(ed, i:number) {
   ed.scrollTo(null, t - middleHeight - 5);
 }
 
+// TODO: https://stackoverflow.com/questions/10463518/converting-em-to-px-in-javascript-and-getting-default-font-size
 function getVisibleEditorLineHeight() : number{
-  return $(".CodeMirror-line:visible").first().height();
+  return $("#booksMenuButton").first().height();
 }
 
 /////
diff --git a/src/workertypes.ts b/src/workertypes.ts
index 06a6d771..606f1688 100644
--- a/src/workertypes.ts
+++ b/src/workertypes.ts
@@ -94,4 +94,6 @@ export interface WorkerResult {
   listings:CodeListingMap,
   symbolmap:{[sym:string]:number},
   params:{},
+  unchanged?:boolean,
 }
+