Description:
The following link provides information on getting debug level Eclipse/studio logs that may be helpful in debugging Design time issues:

    http://www.eclipse.org/eclipse/platform-core/documents/3.1/debug.html

Based on this information, we can get debug level studio logs as mentioned in the Resolution Section.

How to get BW 6.x Studio Console logs (Debug level).

From Command Line:
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1). Start the studio from the command line using the following flags:
        For Windows:   TIBCOBusinessStudio1.exe -console -consoleLog -debug
        For Linux:          ./TIBCOBusinessStudio -console -consoleLog -debug >> StudioDebug.out

2). For Windows OS, modify the screen buffer size of the TIBCOBusinessStudio.exe console so that it wil contain the entire logs.

3). Reproduce the issue.

    For Windows OS you can copy console logs to a text file and then send it to a support team.
    For Linux OS you can redirect these logs to a text file as mentioned in step #1, then send us the StudioDebug.out file.

Setting it as default:
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If you want to set them as default so that whenever you start Studio you'll get logs, you can perform the following steps:         

1). Open the <BW_HOME>/studio/3.6/eclipse/ TIBCOBusinessStudio.ini configuration file and add three more arguments (-console, -consoleLog, -debug) to it between <BW_HOME>/studio/3.6/eclipse & -vmargs:
    For example.
        C:/bw61/studio/3.6/eclipse
        -console
        -consoleLog
        -debug
        -vmargs

2). Start Studio. This should open a new console window (TIBCOBusinessStudio.exe) logging at debug level Studio logs with default Eclipse start up screen showing the Workspace Launcher.
3). Modify the screen buffer size of the TIBCOBusinessStudio console accordingly.
4). Once the issue is reproduced, you can copy the console logs to a text file then send it to the support team.

If you are looking for project logs, they are available in <PROJECT_HOME>/.metadata/.log file.

http://www.eclipse.org/eclipse/platform-core/documents/3.1/debug.html