FF 29 square tabs quick'nDirty

user.css

/*
§	`sharp` corners
*/
.arrowscrollbox-scrollbox {
	-moz-padding-start: 0 !important;
}

.tab-background-middle,
.tab-background {
	-moz-margin-start: 0; 
	-moz-margin-end: 0;
	border-radius: 5px 5px 0 0;
}

.tab-background-middle {
	border-right-style: none;
	border-left-style: none;
}

.tab-background-end,
.tab-background-start {
	visibility: collapse;
}


.tabbrowser-tab:hover > .tab-stack > .tab-background:not([selected=true]),
.tabs-newtab-button:hover {
  background-image: none;
}