Random component overlaps

Hi, we have a bit of a vague problem in which components are sometimes rendered with overlap.
For example, having an horizontal layout with several labels, sometimes all labels are rendered on the left overlapping each other. This happens mostly in IE and sometimes also in FF. It is hard to reproduce; it depends on some factors which we do not yet know/understand. However, if the issue manifests itself, we see that the aboslute positioning in pixels is missing.

This is the HTML being returned in the normal case when everything is fine on the screen:

<div class="v-gridlayout-spacing-off" style="position: absolute;"></div>
<div style="top: 0px; left: 12px;" class="v-gridlayout-slot">
                <div class="v-horizontallayout v-layout v-horizontal v-widget">
                                <div class="v-slot">
                                                <div style="width: 218px; height: 66px;"
                                                                class="v-gridlayout v-layout v-widget">

This is the HTML of the same part on the screen, but this time when the overlapping occurs. As one can see there is no left, top, width or height;

<div class="v-gridlayout-spacing-off" style="position: absolute;"></div>
<div class="v-gridlayout-slot">
                <div
                                class="v-horizontallayout v-layout v-horizontal v-widget">
                                <div class="v-slot">
                                                <div class="v-gridlayout v-layout v-widget">

Anyone an idea what this might be or what is causing it?

We are experiencing the same problem with certain clients that are using IE 11. (Other users of IE11 do not suffer from this problem though). The JS console shows the following error:

SEVERE: Exception caught: (TypeError) : Unable to get property 'ic' of undefined or null referencecom.google.wgt.event.shared.UmbrellaException: Exception caught: (TypeError) : Unable to get property 'ic' of undefined or null reference
        at Unknown.Om(Unknown Source)
        at Unknown.Tm(Unknown Source)
        ...
Caused by: com.google.gwt.core.client.JavaScriptException: (TypeError) : Unable to get property 'ic' of undefined or null reference

We will have to de-obfuscate the widgetset and try again.