Yeah I imagine. 

Ok

I have tabbed panes using 

class CBla : public CWnd
{
....

THis class is a subclass of another class that further defines what the tab does. 

class CDetailed : public CBla
{
....

Each of these panes has two classes derived from XTPToolbar so the toolbars are stacked one above the other in the tab. Each toolbar has a number of XPTComboboxes in it. If I hit tab, the focus shift from toolbar to tool bar. If I then click on the edit of one of the combo boxes, I get a freeze and my CPU load goes through the roof. You can hear my CPU fan spin up too. 

riched20.dll!000007fef8ac804b()
[Frames below may be incorrect and/or missing, no symbols loaded for riched20.dll]
riched20.dll!000007fef8afad41()
riched20.dll!000007fef8afab78()
riched20.dll!000007fef8acaac2()
riched20.dll!000007fef8ad5266()
riched20.dll!000007fef8ad7e3d()
riched20.dll!000007fef8ac1e8a()
user32.dll!000000007706c3c1()
user32.dll!0000000077066484()
user32.dll!0000000077066400()
> Bla.exe!CWnd::DefWindowProcW(unsigned int nMsg=1092, unsigned __int64 wParam=0, __int64 lParam=1242880) Line 1089 + 0x2f bytes C++
  Bla.exe!CWnd::WindowProc(unsigned int message=1092, unsigned __int64 wParam=0, __int64 lParam=1242880) Line 2088 + 0x21 bytes C++
Bla.exe!AfxCallWndProc(CWnd * pWnd=0x0000000005d66150, HWND__ * hWnd=0x0000000000010b2a, unsigned int nMsg=1092, unsigned __int64 wParam=0, __int64 lParam=1242880) Line 257 + 0x30 bytes C++
Bla.exe!AfxWndProc(HWND__ * hWnd=0x0000000000010b2a, unsigned int nMsg=1092, unsigned __int64 wParam=0, __int64 lParam=1242880) Line 420 C++
user32.dll!000000007706c3c1()
user32.dll!000000007706a6d8()
user32.dll!000000007706a85d()
Bla.exe!CXTPControlComboBoxEditCtrl::UpdateCharFormat() Line 1439 C++
Bla.exe!CXTPControlComboBox::OnSetSelected(int bSelected=0) Line 674 C++
Bla.exe!CXTPCommandBar::SetSelected(int nSelected=-1, int bKeyboard=0) Line 525 C++
Bla.exe!CXTPCommandBar::SetTrackingMode(int bMode=0, int bSelectFirst=1, int bKeyboard=0) Line 1273 C++
Bla.exe!CXTPCommandBar::OnTrackLost() Line 1219 C++
Bla.exe!CXTPMouseManager::SendTrackLost() Line 329 C++
Bla.exe!CXTPMouseManager::DeliverMessage(CXTPCommandBar * pCapture=0x0000000005d1e0f0, unsigned __int64 wParam=513, tagPOINT pt={...}) Line 85 C++
Bla.exe!CXTPMouseManager::PreTranslateMouseEvents(unsigned __int64 wParam=513, tagPOINT point={...}) Line 226 C++
Bla.exe!CXTPMouseManager::MouseProc(int nCode=0, unsigned __int64 wParam=513, __int64 lParam=1244144) Line 266 + 0x1e bytes C++
user32.dll!00000000770585a0()
user32.dll!000000007706201b()
user32.dll!0000000077078c51()
ntdll.dll!000000007719f5e5()
user32.dll!000000007706c92a()
user32.dll!000000007706c95e()
Bla.exe!AfxInternalPumpMessage() Line 153 + 0x1a bytes C++

If I run and then break, it always seems to be somewhere near "UpdateCharFormat()"

It doesn't freeze every single time but, it will eventually freeze if you tab and then click on one of the combo-edits. 

15.1.2 but, 15.0.2 had the same issue. It seems like it's posting messages to itself and just processing the same commands over and over again.  It never unfreezes.  I tried the other derived pane type and it has the same symptoms. It seems that if I tab to the other toolbar then click on the first toolbar with the mouse, that causes the freeze.