I had issues with this too. For example, when showing the menu in CR (FW5), the entire display buffer offsets with PanelHeight() pixels.
So I did a dirty workaround for that (being the fact that while the menu is shown, no interaction is allowed with the rest of the app).
I activate the panel without drawing it, take an offset screenshot, redraw the screenshot, draw top & bottom parts of the menu and then update the screen.
If I wouldn't do the screenshot part I'd always get an annoying offset of the page text when toggling menu.
It's not an elegant way of solving things but I was too lazy to go deeper into the problem.
)
PHP Code:
virtual void OpenTouchMenu() {
[...]
// Activate system panel
CRLog::trace("CRPocketBookQuickMenuWindow::OpenTouchMenu(): Activate system panel");
showSystemPanel(false);
// Offset the background
CRLog::trace("CRPocketBookQuickMenuWindow::OpenTouchMenu(): Offset the background");
ibitmap * bkg = BitmapFromScreen(0, PanelHeight(), ScreenWidth(), ScreenHeight()-PanelHeight());
DrawBitmap(0, 0, bkg);
free(bkg);
[...]
// Draw
CRLog::trace("CRPocketBookQuickMenuWindow::OpenTouchMenu(): Draw");
DrawTop(false);
DrawBottom(false, -1, -1);
// Update screen
CRLog::trace("CRPocketBookQuickMenuWindow::OpenTouchMenu(): PartialUpdate(0, 0, %d);",
ScreenWidth(), ScreenHeight());
PartialUpdate(0, 0, ScreenWidth(), ScreenHeight());
}