An example of Sigil use: I recently had to do some internal structural changes on all our titles - around 300 - due to some changes of the distribution system we use. It took me at weekend - give or take - using a combination of Sigil and AutoHotkey. Without Sigil this might have taken weeks, and I probably would have had acquired a tennis elbow from the processing.
BTW, I have tried to download the Sigil code to take a look, but I get stuck when using cmake with an error "Qt5-dir not found" and
"CMake Error at src/Sigil/CMakeLists.txt:454 (qt5_wrap_ui):
Unknown CMake command "qt5_wrap_ui"."
QT 5.1.1. is installed in C:\Qt\Qt5.1.1 (default). I'm not a C++ programmer by nature, and certainly not cross-platform, so I can't get any further. (Made some small programs and databases in Object Pascal/Delphi in the 90's and early 00's, but since then it's been Office VBA and Lotus Notes - but I might be able to make some small contributions - learning is a life-long proces, ain't it
)
Regards
Kim