code: public void recalcContentHeightPercent() {
          if (stopPartsPositioning) return;
          if (!isVisible()) return;
          Element contentElt = content.getElement();
          if (contentHeightPercent > 0) {
              final JQMHeader header = getHeader();
              final JQMFooter footer = getFooter();
              int headerH = header == null || isFixedToolbarsHidden() ? 0 : header.getOffsetHeight();
              int footerH = footer == null || isFixedToolbarsHidden() ? 0 : footer.getOffsetHeight();
              int windowH = Window.getClientHeight();
  
              int clientH = contentElt.getPropertyInt("clientHeight");
              int offsetH = contentElt.getPropertyInt("offsetHeight");
              int diff = offsetH - clientH; // border, ...
              if (diff < 0) diff = 0;
  
              double h = (windowH - headerH - footerH - diff) * 0.01d * contentHeightPercent;
              h = Math.floor(h);
              contentElt.getStyle().setProperty("minHeight", String.valueOf(Math.round(h)) + "px");
              contentElt.getStyle().setProperty("paddingTop", "0");
              contentElt.getStyle().setProperty("paddingBottom", "0");
          } else {
              contentElt.getStyle().clearProperty("minHeight");
              contentElt.getStyle().clearProperty("paddingTop");
              contentElt.getStyle().clearProperty("paddingBottom");
          }
      }
docs: Forcefully recalculates (if defined, and just once) page content height
  (needed when content area size is changed, because there is no good way to get resize
  notification for DOM elements).