HorizontalPanel in GWT - gwt

Question

I have added a Label and a ListBox in a HorizontalPanel as a header of a web page. When I set the left margin of a label and the right margin of a listbox and change the size of the window, their positions change. It would be great if anyone can help me to solve this problem.
HorizontalPanel hp = new HorizontalPanel();
Label label = new Label("Test Program");
label.addStyleName("test-label");
ListBox listbox = new ListBox();
listbox.addItem("test1");
listbox.addItem("test2");
listbox.addStyleName("test-listbox");
hp.add(title);
hp.add(language);
CSS file:
.test-label{float:left}
.test-listbox{float:right}

Answer 1

I tried you code setting the HorizontalPanel to a 100% width. I tried adding margins to the elements and they work fine. Please note i suspect your vanish behaviour might be due to rogue additions
**hp.add(title);**
**hp.add(language);**
Your declarations have label and listbox and you are adding title and language.
Sample Code :
HorizontalPanel hp = new HorizontalPanel();
hp.addStyleName("testWidth");
Label label = new Label("Test Program");
label.addStyleName("test-label");
ListBox listbox = new ListBox();
listbox.addItem("test1");
listbox.addItem("test2");
listbox.addStyleName("test-listbox");
hp.add(label);
hp.add(listbox);
RootPanel.get().add(hp);
CSS
.test-label {
float: left;
margin-left: 10px;
}
.test-listbox {
float: right;
margin-right: 10px;
}
.testWidth{
width: 100%;
}