I have a field with the id "FormHelper-X+n-I". When I select it using "FormHelper-X
+n-I" as Selector, the datepicker opens, but I cannot choose any date.

Using tooltip widget with document as selector removes text in <title></title> when the tooltip widget is disabled.

The dialog titlebar type seems to be set too low. An even .4em on top and bottom still achieves a total padding height of .8em but sets the type correctly and more consistently with other widgets (note typesetting on accordion header, for example). I can't find mention of this on the forum or in past tickets. Current css uses this padding on the div:

.ui-dialog .ui-dialog-titlebar {
    padding: 0.5em 1em 0.3em;
    position: relative;
}

and this margin on the child span:

.ui-dialog .ui-dialog-title {
   margin: 0.1em 16px 0.2em 0;
}

Sent pull request on github.