Problem with oF multiwindow and textures

GuiApp.cpp

// in GuiApp.h:
// ofFbo fbo2;


void GuiApp::setup(){
    parameters.setName("parameters");
    parameters.add(radius.set("radius",50,1,100));
    parameters.add(color.set("color",100,ofColor(0,0),255));
    gui.setup(parameters);
    ofBackground(0);
    ofSetVerticalSync(false);

    fbo2.allocate(100,100);
}

void GuiApp::update(){
    fbo2.begin();
    ofClear(0);
    ofFill();
    ofSetColor(255,0,0);
    ofDrawRectangle(0,0,100,100);
    fbo2.end();
}

void GuiApp::draw(){
    gui.draw();

    fbo.draw(0,0);
}

ofApp.cpp

// in ofApp.h:
// ofFbo fbo;

void ofApp::setup(){
	ofBackground(255);
	ofSetCircleResolution(200);

        fbo.allocate(100,100);
}

//--------------------------------------------------------------
void ofApp::update(){
    fbo.begin();
    ofClear(0);
    ofFill();
    ofSetColor(255,0,0);
    ofDrawRectangle(0,0,100,100);
    fbo.end();
    
    ofSetColor(255);
}

//--------------------------------------------------------------
void ofApp::draw(){
    
    ofSetColor(gui->color);
    ofDrawCircle(ofGetWidth()*0.5,ofGetWidth()*0.5,gui->radius);
    ofSetColor(0);
    ofDrawBitmapString(ofGetFrameRate(),20,20);

    fbo.draw(0,0);
}