Fixes to avoid "no Parent-Window" exception

BernhardGeyer

Please change following code to avoid above exception unter some circumstances:

ElPgCtl.pas

TElPageControl.ChangeActivePage -> Add "if HandleAllocated then" bevore Realign
TElPageControl.IntMouseDown -> Add try..except around SetFocus
TElPageControl.IntLButtonUp -> Add try..except around SetFocus
TElPageControl.RecalcTabPositions -> Change "if HasVP then" to "if HasVP and HandleAllocated then"

ElTree.pas

TElTreeItem.RedrawItemPart -> Add "if FOwner.FView.HandleAllocated() then" bevore InvalidateRect
TElTreeItem.RedrawItem -> Add "if FOwner.FView.HandleAllocated() then" bevore InvalidateRect

Alexander Hramov

Added. Thank you.