I would imagine the following behaviour after using the Find Files command (some of the features below are already present in the current version):
1. The Search for field is shown always cleared.
2. The Find for checkbox is shown always unchecked.
3. The Find for combobox is shown always enabled, focused, with the previously used contents fully selected.
4. The Find for combobox watches the changes in the contents and simulates the click on the Find for checkbox if a change occurs, unless the change results in the combobox field becoming empty - then the checkbox becomes unchecked.
5. The other controls in the Find for section are enabled/disabled according to the state of the Find for checkbox.
Some usability scenarios (assuming the changes described above as already implemented):
1. The user wants to find all files in the current directory containing a certain text.
Alt-F7, type the text to search for (the checkbox becomes checked automatically while typing), Enter
Currently an additional click on the checkbox is needed.
2. The user wants to find all files having a certain file name mask (e.g. A*.cs), containing a certain text
Alt-F7, type the text to search for (the checkbox becomes checked automatically while typing), click on the Search for combobox, type the file name mask, Enter
Currently a similar amount of input must be provided (although the workflow is different):
Alt-F7, type the file name mask, click on the Find text combobox, type the text to search for, Enter
3. The user wants to find all files having a certain file name mask, but does not care about using Find text feature
Alt-F7, click on the Search for combobox, type the file name mask, Enter
Currently, one LESS click is required, as the Search for combobox is readily available.
Summing up, all depends on which facilities are used most frequently. If the user searches mainly for text, my approach seems to be more ergonomic. If the user searches mainly for files having a certain file mask, then the original design is better. On the other hand, we have now the Quick search feature, which in most cases can replace this part of the Alt-F7 functionality, especially if we include the use of Ctrl-S, reducing the number of file names displayed in the panel to those matching the file mask. (especially as the wildcards can be used

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In view of the above, I think it is worthwhile implementing the new workflow, as in the average it should improve the ergonomics of TC: for some of us only a bit, for the others quite substantially
We could always have yet another configuration option (I think Christian must hate them by now!), allowing the user to chose between these two approaches.